LTC4S and colonic neoplasm: We found sequences in the CysLT2R promoter region that were identical to RAREs reported in the literature and hypothesized that treatment of colorectal cancer cells with ATRA would affect the expression of CysLT2R. Furthermore, we investigated whether ATRA-induced colon cancer cell differentiation was dependent on CysLT2R. LTC4S conjugates LTA4 with glutathione to form LTC4[3], and is induced by ATRA in rat basophilic leukemia cells and associated with subsequent cell differentiation [29].