N2'-Deacetyl-N2'-(4-mercapto-4-methyl-1-oxopentyl)-maytansine;Maytansine,N2'-deacetyl-N2'-(4-mercapto-4-methyl-1-oxopentyl)-;DM4top3;MertansinChemicalbookeImpurity1;N2'-Deacetyl-N2'-(4-mercapto-4-methyl-1-oxopentyl)-maytansine(DM4);TheelementDM4;Benzoicacid,5-(chlorosulfonyl)-4-methyl-;Ravtansine