RPMI 1640, HEPES, staurosporine, Hoechst 33342, and
3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide
were purchased from Sigma–Aldrich, St. Louis, USA. Fetal
bovine serum was supplied by Gibco, USA. All solvents were
HPLC grade and supplied by J.T. Baker