CCND1 and urinary bladder cancer: Even though the detailed mechanisms by which COP represses the expression level of CCND1 in bladder cancer have not been fully explained, increasing evidence shows that CCND1 is positively regulated by PI3K/AKT pathway, mTOR pathway and GSK3β pathway [41–44], implying that the regulator network among COP, PI3K/AKT, and GSK3B contributes to the dysregulation of CCND1 in bladder cancer cells.