Correlation between PRL-3 level and ERK phosphorylation. (A) PRL-3 enhanced ERK1/2 phosphorylation in LoVo cells. Equal numbers of LoVo-C and LovO-P cells were cultured for 24 h with complete medium. Cells were harvested and lyzed. Then cell lysates (50 μg of protein) were subjected to Western blot with antibodies against p-ERK1/2, ERK1/2, Myc-tag (for Myc-PRL-3), integrin β1, and GAPDH, respectively. (B) Expression of PRL-3 and p-ERK1/2 in primary lesions of human colon cancer tissues was analyzed by an immunohistochemical assay. Two consecutive 4-μm paraffin-embedded slices of the same tissue sample were probed with anti-PRL-3 (a, c, e, g) and anti-p-ERK1/2 (b, d, f, h), respectively. The representative negative staining of PRL-3 and p-ERK1/2 in the consecutive slices was shown in a and b, and the representative positive staining of PRL-3 and p-ERK1/2 was shown in the c, d, e, f, g, h (c and d, without HE counterstaining; e, f, g, h, with HE counterstaining; g and h, enlarged views of e and f, respectively).