SLC7A5 and cancer: In colonic cells, MYC promotes the expression of the tryptophan transporters (SLC7A5 and SLC1A5) and enzyme arylformamidase in the kynurenine pathway, thereby driving the conversion of tryptophan into kynurenine.34 Of note, high levels of kynurenine can increase the proliferation and migratory capacity of cancer cells, and help tumors escape immune surveillance.35