SPTLC2 and nonpapillary renal cell carcinoma: Furthermore, to impede SM synthesis, we also employed lentivirus-mediated knockdown systems targeting Serine Palmitoyltransferase Long Chain Base Subunit 2 (SPTLC2), a pivotal enzyme responsible for initiating the de novo synthesis of SM26, in SETD-mut ccRCC cell line CAKI-1.