SRC and obesity due to melanocortin 4 receptor deficiency: The core targets between estrogen and obesity are proto-oncogene, non-receptor tyrosine kinase (SRC), estrogen receptor 1 (ESR1), prostaglandin-endoperoxide synthase 2 (PTGS2), nuclear receptor subfamily 3 group C member 1 (NR3C1) and cytochrome P450 family 19 subfamily A member 1 (CYP19A1).