DICER1 and plasma cell myeloma: To determine whether myeloma cells could affect MSCs, HC-MSCs were co-cultured with myeloma cell lines (such as NCI-H929, OPM-2, and KMS-12-BM) or with primary CD138+ tumors cells from three MM patients for 24 h and the expressions of Dicer1, p21, miR-93 and miR-20a was determined by RT-PCR.