ICMT is a metalloenzyme [§§]; locus: 1p36 the functional human homolog of Ste14 (a farnesylated form of STE24 prelamin forming (ste24-null/Lmna) mature lamin) in the endoplasmic reticulum and nuclear membrane ICMT the prenylation pathway the third of three enzymes. And consists of three enzymatic steps and in one of its substrates, the RhoGTPase Rac1 appears to be the only enzyme participating in the carboxyl methylation of isoprenylated proteins. After farnesylation (FTase), Rheb undergoes two additional CAAX-signaled processing steps. Overexpression of ICMT inhibited apoptosis [adenosine] Ado/Hy [homocysteine] which does not require carboxyl methylation inhibition of ICMT causes endothelial cell apoptosis followed by RCE1 proteolytic cleavage of the CAAX peptide and carboxyl methylation by proteolysis, or by the Ras converting enzyme Rce1. Because carboxyl methylation [CAAX] of Ras is important for proper plasma membrane localization for membrane attachment that confers resistance to and causes endothelial cell apoptosis (N-acetyl-S-farnesyl-L-cysteine (AFC) or N-acetyl-S-geranylgeranyl-L-cysteine (AGGC)) restricted on mitogen-activated protein to the endoplasmic reticulum.