PROK1 induces LIF mRNA and protein expression. LIF mRNA (A) and protein (B) expression in WT and PROKR1 Ishikawa cells after treatment with 40 nM PROK1. LIF mRNA and protein expression peaked at 6 and 12 h, respectively, in PROKR1 Ishikawa cells. No elevation in LIF mRNA expression was observed in WT Ishikawa cells. Expression of LIF mRNA (C) and protein (D) was measured after treatment with 40 nM PROK1 (lane 1) in the absence or presence of YM254890 (Gq inhibitor, lane 2), BAPTA-AM (calcium inhibitor, lane 3), PKC inhibitor (Ro-318220, lane 4), cSrc inhibitor (PP2, lane 5), EGFR inhibitor (AG1478, lane 6), or MEK inhibitor (PD98059, lane 7). PROK1-induced LIF mRNA and protein expression was significantly inhibited in the presence of these inhibitors. Bars represent means ± se of at least 3 independent experiments. *P < 0.05. ns, not significant; −, absence of agent; +, presence of agent.