GSTP1 and hepatocellular carcinoma: The NRF2 activation of the STCs was elucidated by determining the NQO1 induction (Prochaska microtiter plate assay) and expression of representative antioxidant genes (HMOX1, NQO1, GCLC, GCLM, TXNRD1, PRDX1, GPX2, GSTP1, GSTM2, GSTA1, and G6PDX by qPCR) in mouse hepatoma (Hepa-1c1c7) cells.