CYP2S1 and thyroid cancer: To determine whether CYP2S1 serves as a synthetic lethal partner of BRAFV600E in thyroid cancers, we first knocked down CYP2S1 expression in four BRAFV600E-mutated thyroid cancer lines (BCPAP, 8305C, 8505C, and K1) and two BRAF wild-type thyroid cancer cell lines (C643 and TPC-1), as shown in Fig. 2a.