IGF2 and breast cancer: It should be noted that miR-100 has been reported to target IGF2 in 4T1 mouse mammary tumor cells [40]; however, IGF2 expression is undetectable in the human mammary epithelial cells (HMLE) used in this study (data not shown), although it is possible that IGF2 mediates the function of miR-100 in cells that express IGF2.