The activation of NEK2 in myeloma cells relied on the ALDH1A1-dependent generation of the retinoid X receptor α (RXRα) ligand, 9-cis retinoic acid (9CRA) – not the retinoic acid receptor α (RARα) ligand, all-trans retinoic acid (ATRA). This evidence concerns the gene ALDH1A1 and plasma cell myeloma.