MicroRNAs are small non-coding RNAs which regulate gene expression by binding to 3&rsquo / UTR of their target mRNAs. Deregulated expression of microRNAs is detected in many pathologies including different types of cancers. miR-106b, is a member of miR-106b-25 cluster and overexpressed in many cancers including breast cancer. Based on miR-106b overexpression, we hypothesized that miR-106b may be an oncogene candidate. To explore miR-106b related phenotypes, we used an already miR-106b transfected model cell line system. Stably transfected MCF10A cells were investigated for alterations in cell growth, motility, migration and invasion. Our results showed that miR-106b overexpression caused increased growth motility and migration. On the other hand, based on matrigel invasion assay miR-106b expression caused a reduction in cell invasion. Further studies are needed to be performed to understand the precise role of miR-106b in breast cancer. Studies are underway to detect possible miR-106b targets that may help to explain these phenotypical alterations.