Correlation of claudin-6 and ASK1 in breast cancer cells. Line 1 is empty vector group; lines 2, 3 and 4 are three clone groups. (A) (B) RT-PCR assay examined the mRNA levels of claudin-6 and ASK1. (C) (D) Western blot assay detected claudin-6 and ASK1 protein expression. *,**P<0.05, vs. vector group. Results are means ± standard deviation for three independent experiments.