To assess the selectivity of SLC16A3/MCT4 inhibitor slCeMM1, we derived diazirine-alkyne photoaffinity probe (slCeMM1-PAP). We next used HAP1 and MDAMB231 cell lines for MS experiment, comparing the enrichment of proteins by slCeMM1-PAP and conditions where slCeMM1-PAP was competed with slCeMM1 or it’s structurally related inactive control (S1_007). We found that among proteins enriched by slCeMM1-PAP, only SLC16A3 was competed by slCeMM1, but not S1_007, confirming the SLC16A3 engagement by slCeMM1 and suggesting overall good selectivity of slCeMM1.