MAPK7 and plasma cell myeloma: Our data from 3MC-derived cell lines suggest that sarcoma, or at least pathologies such as leiomyosarcoma, should be included in the list of tumors in which ERK5 plays a determinant role, as for example, hepatocellular carcinoma [47], breast cancer [38,48], lung cancer [49], or myeloma [26], among others.