BIRC6 and urinary bladder cancer: CircRNA-baculoviral IAP repeat-containing 6 (circ-BIRC6) is the product of back-splicing of the BIRC6 transcript from chromosome 2 that participates in cell proliferation, colony formation, and invasion in cancers such as hepatocellular carcinoma and bladder cancer (Zhou et al., 2021[145]; Yang et al., 2019[125]).