ERBB2 and breast cancer: To determine which breast cancer subtypes are characterized by elevated CERS4 mRNA, the datasets were reanalyzed according to breast cancer subtype, revealing significantly higher CERS4 mRNA expression in LumA than in non-LumA (LumB, HER2-positive, and basal) subtypes across all three cohorts (TCGA-BRCA, P < 0.0001; GSE115577, P = 0.007; GSE96058, P < 0.0001; Fig. 1B).