TLR4 and cancer: A key advancement in reconciling MSCs functional duality in cancer came from Waterman et al. [15], who demonstrated that MSCs can be polarized into two distinct phenotypes: MSC1, a pro-inflammatory and tumor-suppressive phenotype induced by low-dose lipopolysaccharide (LPS) via Toll-like receptor 4 (TLR4) over a short period of time, and MSC2, an immunosuppressive and tumor-promoting phenotype induced by poly(I:C).