FIG. 4.

CP-31398 inhibits the ubiquitination of p53. (A) H460 and PA-1 cells were treated with CP-31398 (CP) at a concentration of 15 μg/ml for 1 h, and then ALLN was added at a concentration of 50 μM. Four hours later, cells were lysed for Western blotting with DO-1 against p53. (B) Dose-dependent inhibition of p53 ubiquitination by CP-31398. (C) Same H460 cell lysates as in panel A, probed with an anti-ubiquitin antibody (Santa Cruz). (D) Immunoblots against pRB, smad2/3, and cyclin E in H460 cells after treatment with adriamycin (ADR) or CP-31398. Lanes C, control.