Effect of protein kinase inhibitors on hemin-induced Ngb expression.

HN33 cells were treated for 1 hour with protein kinase inhibitors at the indicated concentrations and then with 50 μM hemin for 24 hours. Western blotting was used to detect Ngb protein expression (panel A), which was quantified by computer densitometry (panel B). Quantitative RT-PCR was used to detect Ngb mRNA expression (panel C), which was quantified by computer densitometry and normalized to the expression of β-actin (panel D). Data are representative blots (panels A, C) or mean ± SEM (panels B, D) from 3 experiments. Con indicates control; KT, KT5823 (PKG inhibitor); LY, LY83583 (sGC inhibitor); GF, GF109203X (PKC inhibitor); and PD, PD98059 (MEK inhibitor). *P < .05 compared with both control (unfilled bar) and hemin. **P < .001 compared with control (unfilled bar), but not with hemin.