The role of miR-205 is rather complex, since it can act either as an oncogene or a tumor suppressor gene under different cell contexts.28 In this paper, we have observed the G2/M arrest in T24 cells with overexpressed miR-205, and identified a mitosis controlling cyclin, CCNJ, which was downregulated by miR-205 via targeting its 3′UTR, as a novel target of miR-205 in bladder cancer. Here, CCNJ is linked to urinary bladder cancer.