For example, miR-520b suppressed tumour formation in breast cancer and hepatocellular carcinoma by targeting MAP3K2 and cyclin D1, miR17/20a inhibited tumour growth via targeting the MAP3K2-Erk5 pathway in vivo43, and miR-26a promoted glioblastoma cell growth in vitro via targeting MAP3K230. This evidence concerns the gene CCND1 and breast cancer.