Given the potential role of CXCR4 in tumor growth and dissemination (Alsayed et al, 2007; Roccaro et al, 2015), its increased expression upon Dex exposure in a subset of MM.1S cells that do not express the proapoptotic gene BCL2L11 (Fig 6) raises the provocative possibility that minor populations of myeloma cells could proliferate in response to Dex. This evidence concerns the gene BCL2L11 and plasma cell myeloma.