To elucidate the pathways conferring migration and invasion to aggressive CD49f+/CD44+/CD24− single-cell derived clones, we used a PCR array to screen miRNAs in aggressive clone that are associated with breast cancer S2B11 and non-aggressive clone S2D10 and identified six miRNAs that were differentially expressed between these clones. The gene discussed is CD44; the disease is breast cancer.