SLC1A5 and metastatic neoplasm: The expressions of both cystine transporters (SLC7A11, SLC3A2) and cysteine transporters (SLC1A4, SLC1A5) were significantly upregulated in CRC compared with paired non-tumor tissues (Fig. 2C and S3A), but were similar in primary tumors and metastatic tumors (Fig. S3B).