DOX, VCR, CAPE, and MG-132 significantly reduced PL104 cell growth. Cell growth inhibition assessed by [3H]TdR incorporation at 24 and 48 hours after exposure to different concentrations of DOX (A VCR (B), CAPE (C), and MG-132 (D). Results are expressed as percentage of cell proliferation inhibition for each treatment (for additional details, see Materials and Methods). Bars, mean ± SD of at least three independent experiments (***P < .001).