CXCR4 and breast carcinoma: Furthermore, the heteromers have been implicated in the regulation of various physiological processes, such as T lymphocyte chemotaxis48 or breast cancer cellular migration49 for CXCR4-CXCR7 and cardiac myocyte contractility and myocyte survival in heart disease progression47 for β2-adrenoceptor-CXCR4.