THC is more effective in serum-free medium.

(A) EL-4 tumor cells were cultured in serum-free medium in the presence of various concentrations of THC (1, 3, and 5 μM) or the vehicle for 4, 8, or 12 hours. The number of viable cells was determined by trypan blue dye exclusion. The data represent the mean ± SEM of duplicate wells. (B) EL-4 tumor cells were cultured in serum-free medium in the presence of vehicle control (DMSO) or THC (5 μM) for 4 hours. The level of apoptosis induction was determined using the TUNEL method. (C) EL-4 cells cultured with THC as described above were stained with annexin V/PI and analyzed using a flow cytometer.