HCAR2 and breast carcinoma: However, the strongest differential mRNA expression of HCA1 (Figure 2A), HCA2 (Figure 2B) and HCA3 (Figure 2C) was detected in breast cancer patient versus normal tissue samples, with HCA1 showing about 5-fold, HCA2 about 2-fold and HCA3 about 3-fold higher mRNA expression levels (Figure 2A-C).