CELSR2 is postulated to be a receptor involved in contact-mediated communication; however, its expression and function in cancer remain unknown. ING4 is a tumor suppresor encoded by the ING4 gene which inhibits cell growth. The expression of CELSR2 and ING4 in breast tumors and in benign epithelial cells have been analyzed and correlated with HER2, ER, and PR status. Immunohistochemistry was used to analyze the expression of CELSR2 and ING4 protein in breast tumors and benign epithelial cells. The differential cellular localization of both markers was analyzed and results were also correlated with HER2, ER, and PR status. CELSR2 and ING4 cytoplasmic expression was significantly stronger in tumors than in benign epithelial cells, while the nuclear expression of both markers was significantly stronger in benign epithelial cells than in tumors. When comparing the two markers in the same type of tissues, the nuclear expression of CELSR2 was significantly stronger than cytoplasmic in benign epithelial cells, while there was no significant difference in the cellular localization of CELSR2 in tumors. For ING4, the cytoplasmic expression was significantly stronger than nuclear expression in tumors, while in benign epithelial cells, ING4 was expressed at similar levels in both compartments. There was no correlation between CELSR2 expression and HER2, ER, and PR status in tumors. However, the cytoplasmic expression of ING4 was associated with HER2 positivity in tumors. Both CELSR2 and ING4 display increased cytoplasmic staining in breast cancer cells compared to benign epithelium, suggesting a possible role of both genes in the pathogenesis of human mammary neoplasia.