BDNF and major depressive disorder: Also in this list are additional proteins [i.e., Apolipoprotein CIII (APOCIII), Brain-Derived Neurotrophic Factor (BDNF), cortisol, Epidermal Growth Factor (EGF), and Prolactin (PRL)] that have been previously associated with depression in other samples.[47–48] TARCC’s remaining protein biomarkers were related neither to the GDS, nor to dEQ.