Effect of flavopiridol on p53, bcl2, and bax proteins. Exponentially growing SUDHL4 cells (A) and PC3 cells (B) were treated with 500 nmol/L of flavopiridol for 1, 3, 6, 18, and 24 hours. Cells were washed with PBS, lysed, and Western blot analysis performed as described in Materials and Methods. Proteins were visualized by autoradiography using ECL. The arrows indicate the position of the bax protein.