PRR4 and breast cancer: S100PBP [68], PRR4 [69], ANKEF1 [39,70], EPCAM [71], SPDEF [72], KRT8, KRT19 [73], KIAA1324 [74,75], CXCR4 [76,77], AGR2 [78,79,80], SCNN1A [81], AP1M2 [82], CLDN4 [83], and ERBB3 [84,85] have been reported to have correlations with breast cancer or have been identified as biomarkers for diagnosis, metastasis, and prognosis of breast cancer and even as therapeutic targets.