The highly lipophilic nature of the conjugate enables its ready passage through the cell membrane; subsequent intracellular cleavage by aminopeptidase N (CD13) releases the active alkylator, in concentrations higher than when melphalan is given alone, to cause irreversible DNA damage and consequent apoptosis in myeloma cells, especially those resistant to melphalan [12]. The gene discussed is ANPEP; the disease is plasma cell myeloma.