FIGURE 2.

Growth inhibitory effects by inhibition of RSK2 in MCL‐derived cell lines. A,B, Growth inhibitory effects of BI‐D1870, an inhibitor of RSK2^Ser227 in the NTKD (A), and FMK, an inhibitor of RSK2‐CTKD (B), on five MCL cell lines. Cells were exposed to various concentrations of BI‐D1870 or FMK for 48 h, and the relative numbers of viable cells were measured by modified MTT assay. IC₅₀ values for the four BI‐D1870‐sensitive cell lines Jeko‐1, KPUM‐YY1, MINO, and Z‐138 were 8.9, 9.5, 5.2, and 7.4 µmol/L, respectively. Data are shown as mean ± SD of three independent experiments. C,D, RSK2 gene knockdown by RNA interference (RNAi) in Jeko‐1 and KPUM‐YY1 cells. Expression levels of RSK2 in RSK2‐knockdown cells (si) relative to those transfected with control siRNAs (Ctl.) are shown as the mean ± SD of three independent experiments (C). Protein levels were measured using Image‐J software (D). E, Numbers of viable RSK2 knockdown cells after 24 h relative to those transfected with Ctl. siRNAs are shown as the mean ± SD of three independent experiments