DHFR and cancer: Due to the high degree of conservation between yeast and human cellular pathways, the results obtained for the yeast dihydrofolate reductase can provide insights into how tumors acquire drug resistance, which is a major barrier to effective cancer treatment [26–28] and point mutations in DHFR active site have been shown to affect MTX binding affinity altering in turn MTX efficacy [8–10,29–37].