Through bioinformatic analysis and in vitro assays, we found that miR-29b expression was reduced by S100A7 in ER− MDA-MB-231 and increased by S100A7 in ER+ MCF7 cells, which at least partly explained the different roles of S100A7 in regulating proliferation of different types of breast cancer cells. This evidence concerns the gene S100A7 and breast carcinoma.