FMR1 and major depressive disorder: Indeed, similar to the report here, two other studies also used Nestin-Cre-ER technology to delete TrkB or fragile X mental retardation protein (FMRP) and found that impaired adult hippocampal neurogenesis by conditional deletion of these endogenous signaling molecules is not associated with depression (assessed by the novelty-suppressed feeding and tail-suspension test, respectively) (Li et al., 2008) or anxiety-like behaviors (elevated-plus maze test) in non-stressed mice (Guo et al., 2011)).