IRS1 and colorectal carcinoma: In an effort to delineate potential downstream targets and further understand the mechanisms of miR-126 down-regulation in the pathogenesis of CRC, we transfected HT-29 cells with an IRS-1 3′-UTR luciferase reporter construct containing a wild type miR-126 putative binding sites (psi-IRS-1) or a mutant construct bearing mutations in miR-126 binding sites (psi-mutIRS-1).