TGFB1 and depressive symptom measurement: Previous gene expression analysis from a cross-sectional post-mortem study has identified multiple differences in CP samples obtained from patients with depression, particularly in the downregulation of genes related to the “transforming growth factors- beta” (TGF-B) pathway, which are known to interact with the production of the extracellular matrix, suggesting changes in the cytoskeleton of CP epithelial cells in patients with MDD (Turner et al., 2014).