Since TGFB signaling and its upstream gene TGFBR2, which has been reported to be a target gene of miR-665 in pancreatic cancer and other cancer cells18,26, have been reported in BC32,33, we interested in whether miR-665 promotes BC metastasis by activating MEK signaling, which is reported to advance BC metastasis34,35. The gene discussed is TGFB1; the disease is breast cancer.