a method was developed by which conjugates of methotrexate ( mtx ) with antibody were prepared via an oligopeptide spacer which , after internalization of the conjugates into the target cells , would be cleaved by lysosomal enzymes to liberate mtx or its derivative ( s ) for entry of the drug into the cytoplasm through the lysosomal membrane .
C0010834
cytoplasm
C0230812
lysosomal membrane