LEP and breast cancer: In particular, LEP has been shown to promote HER2 transactivation and phosphorylation in either HER2 high (the expression on immunohistochemistry, IHC 3+) or low (IHC 1+/2+) expressing BC cell lines (BT-474, SK-BR-3, MCF-7, and ZR-75-1), resulting in BC cells proliferation [46].