Figure 4. SFN-Cys decreased the expressions of CDK4, CDK6 and p-Rb via sustained ERK1/2 phosphorylation. (A–D) Both U87MG and U373MG cells were pretreated with PD98059 (25 μM) for 30 min, then treated with SFN-Cys (30 μM) for 24 h. The expressions of CDK4, CDK6, p-Rb, Rb and pERK1/2 were analyzed by Western blot. Data were shown as means ± SD (n ≥ 3). *, P ≤ 0.01.