Among the mapped top 20 signaling pathways (Figure 6), the retrograde endocannabinoid signaling, Rap1 signaling, AGE-RAGE signaling, Estrogen signaling, oxygen reactive species signaling and VEGF signaling pathways are particularly associated with the development and progression of depression [21,22,23,24,25,26]. This evidence concerns the gene VEGFA and major depressive disorder.