P202 PREVENTS APOPTOSIS IN MURINE AKR-2B FIBROBLASTS

p202 is an interferon (IFN)-inducible, primarily nuclear, phosphoprote in (52-kDa) whose overexpression in transfected cells inhibits colony formation. p202 binds to the retinoblastoma tumor suppressor protein a nd two other members of the pocket family proteins (p107 and p130). Mo reover, overexpression of p202 in transfected cells inhibits the trans criptional activity of E2Fs (E2F-1/DP-1 and E2F-4/DP-1), p53, AP-1 c-F os and c-Jun, NF-kappa B p50 and p65. Here we demonstrate that inhibit ion of endogenous p202 production in murine AKR-2B fibroblasts did not result in an increase in cell proliferation. Instead, these cells exh ibited increased susceptibility to apoptosis in response to decrease i n serum concentrations in the growth medium. These observations are co nsistent with the notion that normal levels of p202 may be needed for the regulation of cell proliferation. (C) 1998 Academic Press.