The growth curves of A549 lung cancer cells and WI-38 cells in the presence of CAPE and irradiation. Exponentially growing cells were treated with or without 6 μg/ml CAPE for 1 h prior to irradiation. Viable cells were counted on day 2, 4, 6 and 8 after treatment. The growth curves were obtained by plotting the number of viable cells as a function of time in culture for 8 days. (a) Growth curves of A549 cancer cells; (b) Growth curves of WI-38 cells. CAPE significantly reduces in vitro cell growth of A549 with or without irradiation, while no inhibition of growth was detected in WI-38 cells. Three independent experiments were performed for these curves. Y axis represents the relative cell count, normalized to the cell numbers on Day 0. * P < 0.05, day 4, 6 and 8, CAPE treated cells verse CAPE- untreated cells.