Previous studies have shown that miR-224 can bind to the tumor suppressors of TNFα-induced protein 1 (TNFAIP1) and Smad4, Raf kinase inhibitor protein (RKIP), apoptosis inhibitor-5 (API-5), PH domain leucine-rich-repeat protein phosphatase 1 (PHLPP1), and PHLPP2 to promote the survival and proliferation of colorectal cancer (CRC) and hepatocellular carcinoma (HCC), but bind to the TRIB1 to promote apoptosis of prostatic cancer cells [7–11]. The gene discussed is SMAD4; the disease is prostate cancer.