Expression of bcl-2, bax, and bcl-x in response to ATRA in TF1-neo, TF1-L, and TF1-S cells. (A) Cells were treated with vehicle alone (ethanol [−]) or ATRA (10⁻⁶ mol/L; [+]) for 96 hours; equal amounts of total cellular protein were electrophoresed and immunoblotted successively with antibodies to bcl-2, bcl-x, or bax. The blots were then reprobed with an actin antibody to control for variations in loading and transfer. A representative Western blot is shown. (B) Quantitation of data from four independent experiments with two different TF1-neo, TF1-S, and TF1-L clones. Shown is the average level of bcl-2 expression (±SEM) under control conditions (EtOH; ▪) or after 96 hours of ATRA treatment (ATRA; □), compared in all cases to the bcl-2 expression level in TF1-neo clones under control conditions (value arbitrarily set at 100%). Values were corrected for differences in loading and transfer by incorporating the actin control in the calculation.