FGFR1 and major depressive disorder: A recent alternative hypothesis suggests that depression results from alterations in receptor activity due to formation of homoreceptor and heteroreceptor complexes involving receptor types including 5HT1A, 5HT7, galR1, and fibroblast growth factor receptor 1 (FGFR1) (Borroto-Escuela et al., 2010, 2012; Renner et al., 2012).