Figure 1. Effect of ribociclib in breast cancer cell lines and hormone-resistant cell lines.

(A) Cell proliferation assay of each subtype of breast cancer cell lines treated with ribociclib for 3 days was measured relative to the negative control (treated with DMSO). The results are presented as mean ± standard deviation (SD), and P < 0.05 was considered significant. (B) Protein expression levels of cell-cycle regulatory agents were analyzed using western blotting, with β-tubulin as a protein loading control. (C) Cell proliferation of hormone-resistant breast cancer cell lines treated with ribociclib for 3 days was measured relative to the negative control. (D) Protein expression levels of CDK4 and CDK6 were analyzed by western blotting with β-tubulin as a protein loading control.