Synonyms: 4,24-Dioxa-9,22-diazatetracyclo[19.3.1.110,14.03,5]hexacosane,maytansine deriv.; L-Alanine, N-acetyl-N-methyl-,11-chloro-21-hydroxy-12,20-dimethoxy-2,5,9,16-tetramethyl-8,23-dioxo-4,24-dioxa-9,22-diazatetracyclo[19.3.1.110,14.03,5]hexacosa-10,12,14(26),16,18-pentaen-6-ylester, [1S-(1R*,2S*,3R*,5R*,6R*,16E,18E,20S*,21R*)]-; MTS; Maitansine;Maysanine; Maytansin; N-Acetyl-N-methyl-L-alanine [1S-(1R*,2S*,3R*,5R*,6R*,16E,18E,20S*,21R*)]-11-chloro-21-hydroxy-12,20-dimethoxy-2,5,9,16-tetramethyl-8,23-dioxo-4,24-dioxa-9,22-diazatetracyclo[19.3.1.110,14.03,5]hexacosa-10,12,14(26),16,18-pentaen-6-ylester; NSC 153858