While both serine residues were phosphorylated under some circumstances, it was the S118 site that showed a consistent relationship with the tumor growth phenotype in the obese environment (i.e., FGF1 associated with ER S118 phosphorylation in cells from tumors that grow without estrogen supplementation in obesity). The gene discussed is FGF1; the disease is obesity due to melanocortin 4 receptor deficiency.