The selection of the candidate genes was made on the following criteria: their presence in the signatures described by the molecular apocrine meta-analysis as major top candidates and the availability of specific antibodies to the corresponding proteins suitable for immunohis to chemical detection. The accurate diagnosis of breast apocrine carcinoma remains controversial, mainly due to the rather subjective histopathological criteria and the lack of sensitive and specific biomarkers, which can reliably categorize this subtype of breast carcinoma. The strategy we have employed to Pindolol generate protein markers to specifically categorize IAC and potentially be used as targets for therapy, is based on the assumption that these lesions arise from apocrine cells, which in turn are derived from normal breast epithelial luminal cells that have undergone apocrine metaplasia, i.e. transition from breast epithelial cells into an apocrine sweat-gland type of cells. Here we report an analysis of the expression of two novel putative protein biomarkers, FABP7 and HMGCS2, in breast lesions undergoing apocrine differentiation: from Ozagrel benign apocrine metaplasia to invasive apocrine carcinoma. We have found that the lesions with apocrine metaplasia as well as apocrine cysts in breast were highly positive for both HMGCS2 and FABP7 as compared to normal non-apocrine mammary epithelial cells, implying their value as novel biomarkers for breast apocrine differentiation. HMGCS2 and FABP7 in combination with the panel published in our previous studies, 15-PGDH+, HMGCR+ and ACSM1+ may represent the golden standard for defining the breast apocrine phenotype. Expression of FABP7 and HMGCS2 by invasive apocrine cancer was further demonstrated by IHC using a well characterized set of apocrine carcinomas in which more than 90% of the tumor cells exhibited cytological features typical of apocrine cells. FABP7 positives were found in 78% of all IAC cases and in 96% of ADCIS and only in 14 out of the 210 non-IAC breast tumor subtypes. Tang and coauthors reported that FABP7 overexpression exhibited a strong relationship with triple-negative cases and the basal-like subtype.