KRT5 and breast cancer: A further study described primary breast cancer with neuroendocrine differentiation with a triple negative phenotype without baseline characteristics (negative immunoreactivity for cytokeratin 5/6, cytokeratin 14, and EGFR [20]), which indicated that the genes involved in the migration, invasion, and proliferation of neoplastic cells are under-regulated, giving NEBC a weak ability to metastasize and therefore the NEBC can be grouped with the mucinous carcinoma subtype [2,6].