SAA4 and breast cancer: The Venn diagram of statistically significant (up- and down)regulated proteins shows that seven proteins were found to be commonly altered in all BC subtypes (see Figure 4): apolipoprotein C-III (APOC3), c-reactive protein (CRP), hemoglobin subunit beta (HBB), immunoglobulin heavy variable 3–49 (IGHV3–49), serum amyloid A-4 protein (SAA4), serum amyloid P-component (APCS) and serotransferrin (TF) (Tables S4 and S5).