LPA and ATX/LPC induce OPN expression in SGC7901 cells. (A) Time course of OPN stimulation utilizing ATX (50 ng/ml) + LPC (20 μM) (ATX/LPC2). OPN expression was examined in SGC7901 cells by Western blot and real time-PCR. SGC7901 cells were treated with ATX, LPC, LPA, ATX/LPC1, ATX/LPC2 or DMEM/0.1% BSA. Total protein and RNA was extracted for Western blot (C) and real time -PCR (B), respectively. Figure1 D showed the densitometric ratio of OPN protein/α-tubulin. Statistical analysis was performed using Student's t test. *p < 0.05. The ATX/LPC concentration curve  for stimulated motility provides a justification for the concentrations of ATX/LPC chosen throughout the manuscript. LPA or ATX/LPC stimulates OPN production in additional cell lines (eg, SMMC7721 in our study: ATX-LPA axis induces expression of OPN in hepatic cancer cell SMMC7721) as well as in SGC7901 cells.