CCL21 and breast cancer: From this result, it could be inferred that the CCR7/CCL21 signaling may promote breast cancer chemotaxis to CCL21-producing organs such as lymph nodes, although in this small study, CCR7 mRNA levels did not correlate with breast cancer TNM staging for tumor size (T), spread to lymph nodes (N), and presence of metastasis (M); nor was expression of CCR7 protein on the cell surface confirmed [32].