PRRX1 and breast carcinoma: To determine whether the 3′‐UTR of Prrx1 mRNA is a functional target of miR‐655 in breast cancer cells, the target sequence of Prrx1 3′‐UTR (wt 3′‐UTR) or the mutant sequence (mt 3′‐UTR) were cloned into a luciferase reporter vector (Fig. 6B).