Knocking down any one of SLC7A11, SLC3A2, SLC1A4, or SLC1A5 in HCT116 or DLD1 cells reduced their intracellular cysteine abundance (Fig. 2D–G, S3C-E), suggesting that both cystine and cysteine transporters are important for maintaining intracellular cysteine levels in CRC cells. The gene discussed is SLC1A4; the disease is colorectal carcinoma.