TLR4 and obesity due to melanocortin 4 receptor deficiency: As metabolic deregulation and obesity are known to promote breast tumorigenesis through adverse activation of key cellular elements in tumor stroma, i.e., cancer associated fibroblasts, (CAF) and tumor-associated macrophages (TAM) [6], both expressing TLR4 [58,59], we next examined effects of experimental ME on the stromal compartment of the tumors.