The DP and HaCaT cells were plated in six-well
plates and grown for 12—24 h in DMEM supplemented
with 10% FBS. After washing twice with PBS, the
cells were placed in FBS-free DMEM, together with
1 mCi of [3H]thymidine and the indicated concentrations
of A. radix extract. Following incubation for
48 h, the cells were washed twice with PBS, and
once with 5% cold TCA. The cells were then lysed
with 0.1N NaOH, 1% SDS and the levels of radioactivity
were measured by liquid scintillation counter
(Beckman).