ICMT-IN-48 (compound 1) is an ICMT inhibitor that is competitive (Km=13 μM) for the prenylated methyl acceptor, the first substrate of ICMT. ICMT-IN-48 inhibits ICMT activity with IC50s affected by the concentration of the second substrate S-adenosylmethinine (SAM), and the IC50s are 3.5 μM (1×Km SAM) and 2.3 μM (10×Km SAM), respectively[1].