Figure 1. The effect of ABT263 on the viability of ionizing radiation-induced senescent rat chondrocytes (IR-SC), normal rat chondrocytes (NC) and human OA chondrocytes in culture. (A) Quantification of viable NC at 24, 48, and 72 h after treatment with increasing concentrations of ABT263. (B) CCK8 assay further confirmed that ABT263 showed cytotoxicity to NC after treatment with ABT263 (> 3 μM). (C) CCK8 tests showed a dose-dependent effect of ABT263 on killing IR–SC. (D) Quantification of viable P1 human OA chondrocytes after treatment with increasing concentrations of ABT263 for 24, 48, and 72 h. Data were shown as mean ± standard deviation. N = 3 per group.