Introduction
Explore the compelling history of this vector which has played a pivotal role in cancer research and stands as a lasting tribute to Dr. Morgenstern’s late father, Harold (Babe) Morgenstern.
In the early 1980s, cancer research underwent a significant transformation with the identification of key genes such as the human oncogene RAS1,2. While these discoveries showed activated oncogenes could drive cellular transformation, it quickly became apparent that cancer development was more complex than a single genetic alteration. Researchers began uncovering that malignant transformation typically requires multiple sequential mutations, in a process now known as the multi-step model of carcinogenesis. Studying this multi-step model demanded more sophisticated research tools than were available at the time.
In molecular biology, retroviral vectors are used to introduce genes into mammalian cells to study gene function. While early retroviral systems were effective, they came with significant limitations like unreliable gene expression, low viral titres and viral contamination3. To counter these difficulties, the pBABE vector system was developed during Morgenstern’s PhD at Cancer Research UK’s Lincoln’s Inn Fields laboratory and was later published with Hartmund Land in Nucleic Acid 19903,4. pBABE overcame the limitations of previous retroviral systems by delivering high-titre virus production, stable gene expression, helper-free design and multiple selection markers3. pBABE enabled researchers to introduce and select for multiple genetic modifications sequentially5, facilitating experiments what were previously impractical or impossible.
As a result, pBABE became a foundational technology for a new era of cancer biology. Over the past 30 years, the pBABE vectors have been featured in countless studies and cited in more than 2,150 publications.
The inventor names pBABE after his Father
The creation of the vectors happened to align with Harold Morgenstern’s father’s 60th birthday. Affectionately known as “Babe” — a nickname he earned as the youngest sibling, born during the heyday of Babe Ruth — the vectors were named in his honour.
Figure Legend: pBABE vector map generated with Snapgene.
pBABE Technology
The pBABE system’s effectiveness stems from several key design elements that addressed the limitations impeding previous vectors. Based on the Monkey Murine Leukemia Virus (MoMLV), pBABE incorporated critical modifications that transformed it into the research workhorse it is today3.
One of the pBABE’s key innovations was the 194-splice donor mutation, which prevented unwanted mRNA splicing whilst maintaining high viral titres, exceeding x106 cfu/ml3. Another crucial modification was the ATG-modified gag sequence, that preserved the RNA packaging signals necessary for high viral titres, while eliminating translation of gag proteins that could increase the risk of generating replication-competent retroviruses3.
Gene expression in these vectors is driven by the MoMLV 5’ Long Terminal Repeat (LTR) promoter, this ensures consistent long-term expression, which is critical for cancer studies requiring stable oncogene/tumour suppressor expression3.
Importantly, pBABE vectors were created with four different selection markers3, see Table 1. Including puromycin, pBABE was one of the first to confer puromycin resistance, which significantly reduced the cost of stable selection, when compared to the neomycin/G418 system.
| Vector Name | Selection Agent | Shuttle Vector Capability |
| pBABE-neo | G148/Neomycin | Yes, Kanamycin in bacteria |
| pBABE-puro | Hygromycin B | Yes, Hygromycin in bacteria |
| pBABE-hygro | Puromycin | No |
| pBABE-zeo | Zeocin/Bleomycin/Phleomycin | No |
The complementary ΩE (Omega-E) packaging cell line represented a significant advancement in retroviral technology. ΩE was engineered with a separated gagpol and env expression constructs with minimal sequence overlap and ‘codon wobbling’ to decrease sequence homology3. This design minimised the risk of generating-replication competent retroviruses while maintaining high viral titres3. Together with pBABE vectors, this packaging system provides researchers with a safe, efficient platform that has supported breakthrough studies in cancer biology and beyond.
pBABE breakthroughs and legacy
The pBABE vector system enabled discoveries that transformed cancer biology. For example, Serrano et al.’s landmark 1997 Cell paper used pBABE to demonstrate how oncogenic RAS triggers premature cellular senescence through p16INK4a/Rb and p53/p21pathways6.
This discovery established senescence as a critical tumour-suppressive barrier, reshaping our understanding of cellular response to oncogenic stress.
Following this, Hahn et al. used pBABE to systematically define the minimum requirements for transforming normal cells into cancer cells5. By sequentially introducing hTERT, SV40 Large T antigen and H-RasV12, they evidenced the multi-hit model of carcinogenesis5. A framework that continues to guide cancer-research today.
Enduring use of pBABE
Few scientific tools maintain relevance for decades, yet the pBABE vector system remains an exception. With over 2500 citations on the original 1990 paper*, these vectors have become mainstay tools in molecular biology. Their continued use three decades later, spanning cancer research to stem cell biology, speaks to innovative design of these vectors. Even with the advent of CRISPR technology and advanced lentiviral systems, researchers still reach for pBABE vectors when stable long-term expression is essential.
