COL5A3 and breast neoplasm: Interestingly, high expression levels for both the α3(V) gene COL5A3 (Fig. 10a) and the GPC1 gene (Fig. 10b) are strongly associated with luminal A breast tumours, with expression level distribution of both genes in human breast cancer in the order luminal A>>luminal B>>basal-like (P<0.0001).