Assessing putative cell surface receptors (TLR2 and TLR4) binding with extracellular HMGB1, we found that TLR2, but not TLR4, was upregulated in the CD133− cancer cells when treated with HMGB1+ irradiation cells or rhHMGB1 (Fig. 3a). This evidence concerns the gene TLR4 and cancer.