E2F1 and p53 are dispensable, whereas p21(Waf1/Cip1) cooperates with Rb to restrict endoreduplication and apoptosis during skeletal myogenesis.

We describe temporal and genetic analyses of partially rescued Rb mutant fetuses, mgRb:Rb-/-, that survive to birth and reveal specific defects in skeletal muscle differentiation. We show that in the absence of Rb, these fetuses exhibit increased apoptosis, bona fide endoreduplication, and incomplete differentiation throughout terminal myogenesis. These defects were further augmented in composite mutant fetuses, mgRb:Rb-/-:p21-/-, lacking both Rb and the cyclin-dependent kinase inhibitor p21(Waf1/Cip1). Although E2F1 and p53 mediate ectopic DNA synthesis and cell death in several tissues in Rb mutant embryos, both endoreduplication and apoptosis persisted in mgRb:Rb-/-:E2F1-/- and mgRb:Rb-/-:p53-/- compound mutant muscles. Thus, combined inactivation of Rb and p21(Waf1/Cip1) augments endoreduplication and apoptosis, whereas E2F1 and p53 are dispensable during aberrant myogenesis in Rb-deficient fetuses.

Jiang Z ，Liang P ，Leng R ，Guo Z ，Liu Y ，Liu X ，Bubnic S ，Keating A ，Murray D ，Goss P ，Zacksenhaus E ... -  《DEVELOPMENTAL BIOLOGY》

E2F1 mediates ectopic proliferation and stage-specific p53-dependent apoptosis but not aberrant differentiation in the ocular lens of Rb deficient fetuses.

Liu Y ，Zacksenhaus E 《ONCOGENE》

Functional interplay between p53 and E2F through co-activator p300.

Lee CW ，Sørensen TS ，Shikama N ，La Thangue NB ... -  《ONCOGENE》

Release of cell cycle constraints in mouse melanocytes by overexpressed mutant E2F1E132, but not by deletion of p16INK4A or p21WAF1/CIP1.

Halaban R ，Cheng E ，Zhang Y ，Mandigo CE ，Miglarese MR ... -  《ONCOGENE》

Small contribution of G1 checkpoint control manipulation to modulation of p53-mediated apoptosis.

Canman CE ，Kastan MB 《-》