Loss of Rb proteins causes genomic instability in the absence of mitogenic signaling

Loss of G1/S control is a hallmark of cancer, and is often caused by inactivation of the retinoblastoma pathway. However, mouse embryonic fibroblasts lacking the retinoblastoma genes RB1, p107, and p130 (TKO MEFs) are still subject to cell cycle control: Upon mitogen deprivation, they enter and complete S phase, but then firmly arrest in G2. We now show that G2-arrested TKO MEFs have accumulated DNA damage. Upon mitogen readdition, cells resume...