RB1 and plasma cell myeloma: The increased STAT3 phosphorylation in CD45RO/RB overexpression cells further indicates that CD45 isoforms’ expression patterns affect IL-6-induced myeloma cell proliferation possibly through interactions with different CD45 isoforms, because CD45RO has been indicated to homodimerize more efficiently [51] and more readily with the immunological synapse [52] than with other highly molecular weight isoforms.