TAP1 and colorectal carcinoma: Down-regulation or defective TAP1 expression were observed in primary cancer or autologous metastatic lesions of different disease stages, including in bladder cancer [9], small cell lung cancer [10], glioma [11], prostatic cancer [12], head and neck squamous cell carcinoma (HNSC) [13], breast cancer [14], and colorectal cancer (CRC) [15].