Evaluation of nephrotoxicity induced by total terpenoids from Alismatis Rhizoma on HK-2 cells in vitro and its induction of apoptosis Effects of cytochrome P450 isozymes on aristolochic acid renal cytotoxicity Induction of apoptosis in human renal tubular epithelial HK-2 cells by emodin and mediation of endoplasmic reticulum stress