Effect of ceramide analogs (A) C2, (B) AL6, (C) C6, and (D) C8 on in vitro cell proliferation. The antiproliferative effects of each drug was studied using continuous exposures (144 hours) to the drugs of HMVEC-d, HUVEC, Capan-1, and MIA PaCa-2 cells. Symbols and bars, mean values ± SD, respectively. *P < .05 versus vehicle-treated controls.