PAQR3 and breast cancer: Its expression is reduced in several cancer types (including breast cancer, prostate cancer, glioma, esophageal squamous cell carcinoma, laryngeal squamous cell carcinoma, gastric cancer, NSCLC and colorectal cancer) [65,66,67,69,74,75,128] due to either the hypermethylation of PAQR3 gene promoter [64,129], the increased expression of miRNA targeting PAQR3 [130] or the DDB2-mediated ubiquitination and degradation [131].