Likewise, GPR55 mRNA levels were elevated in basal tumors with respect to the other molecular subtypes of breast cancer (i.e. normal-like, luminal A or B, and HER2-enriched) in two datasets containing a total of 2557 human samples [20, 22] (Figures 1E and 1F), and in basal human breast cancer cell lines with respect to cell lines with other molecular features (Figure 1G). This evidence concerns the gene ERBB2 and breast cancer.