As serum level of resistin is very high in ob/ob mice, and we observed in vitro that resistin is equally partly responsible for causing impairment in the efficacy of DTIC, it is conceivable that even in the absence of leptin, resistin could be involved in impairing the efficacy of DTIC in ob/ob mice, as resistin is very well known to induce drug-resistant phenotype in various cancers [14, 15, 49, 50]. This evidence concerns the gene RETN and cancer.