In breast cancer, the resistance to doxorubicin is associated with the overexpression of fibroblast growth factor receptor 4 (FGFR4), which increases the anaerobic glucose metabolism and activates ERK1/2; both processes determine resistance to doxorubicin, as demonstrated by the chemosensitization elicited by 2-deoxyglucose and the MEK/ERK inhibitor U0126 [101]. This evidence concerns the gene MAPK3 and breast cancer.