CERK and cancer: Interestingly, the initial hit in the pathway, serine palmitoyl transferase long-chain base complex subunit SPTLC2 has a low cancer-literature-relevance score (Figure S3), but catalyzes the rate-limiting step controlling flux of molecules into the sphingolipid pool subject to transformation to downstream products in subsequent steps of the pathway, such as ceramide synthesis by CERS4, or ceramide-1-phosphate production by CERK, which switch the active function of their products relative to substrates, sphingosine, and ceramide, respectively.