Although multiple miRNAs, such as miR-12230, miR-18b31, miR-515-5p32, miR-148a and miR-15210,14, are involved in IGF-1 regulation pathway by directly targeting IGF-1, IGF-1R, IRS-1 or FOXO3a in breast cancer, the effects of IGF-1 induced signaling cascades on miRNA expression in breast cancer has yet to be evaluated. This evidence concerns the gene IRS1 and breast cancer.