The effect of anandamide on the proliferation of the myeloid cell line 32Dcl3. Growth curves of 32Dcl3 cells cultured in the presence of fetal calf serum (A) or serum-free (B). Cells were cultured with no stimulus (○), with 10 μmol/L anandamide alone (▵), with 10 ng/mL IL-3 alone (□), or with IL-3 plus anandamide (▪). Mean cell numbers (±1 × SD) of triplicate experiments are plotted against the number of days in culture. The doubling time in serum-free culture without anandamide was 75 hours and with anandamide was 29 hours. ³H-TdR incorporation data (cpm ±1 × SD) of 32Dcl3 cells cultured in serum containing medium (C) or in serum-free medium (SFM) (D).