KLF11 and major depressive disorder: Exposure to chronic social defeat stress increases KLF11-immunoreactivity in the frontal cortex, medial prefrontal cortex and CA1 in the hippocampus of rats (Duncan et al., 2015) where reduction in hippocampal volume has been found in imaging studies of MDD patients (Bremner et al., 2000; Bremner, 2002; Koolschijn et al., 2009; Cobb et al., 2013).