CASP9 and renal cell carcinoma: p-STAT3 was found in high levels in RCC; however, isoliquiritigenin-treated RCC showed markedly diminished phosphorylated STAT3 levels, decreasing its binding activity, leading to decreased production of cyclin D1 and cyclin D2 levels and decreased cleavage of caspase-3, caspase-7, caspase-9, and PARP.