QKI and prostate cancer: Our current study also demonstrated that QKI‐6 expression is associated with advanced tumour stages of bladder cancer patients, which further validated previous in vitro data showing that QKI suppresses colon and oral tumorigenicity11, 16 and prostate cancer.18 Although there are several QKI isoforms,9, 10 our current findings showed that QKI‐6 was significantly down‐regulated in bladder cancer tissues and cell lines compared to other QKI isoforms.