ESR1 and breast cancer: To further elucidate the functional implication of CAMP in breast cancer, we investigated the expression of CAMP in different breast cancer cell lines (MDA-MB-231: triple-negative breast cancer; MCF-7: estrogen receptor-positive; SK-BR-3: HER2-positive; T47D: estrogen receptor-positive) by qRT-PCR (Figure 2A) and Western blotting (Figure 2B).