SMPD1 and liver cancer: Through thermal proteomeprofiling, the protein sphingomyelin phosphodiesterase 1 (SMPD1) wasidentified as the target of probe 41, with higher mRNAexpression of SMPD1 in THLE-2 cells than in HepG2 cells, which explainswhy probe 40 and probe 41 exhibit high selectivityfor liver cancer cells and healthy liver cells, respectively.