pSrc, pERK, pAkt, pS6K, and caspase 3 expression in HK-2 cells after ouabain treatment. pSrc, pERK, pAkt, pS6K and caspase 3 expressions were determined by western blot, which showed that they were all activated after ouabain treatment (A-F). Comparisons were determined by t-test. *P<0.05, **P<0.01, ***P<0.001.