ABCA1 and plasma cell myeloma: Then, ABCA1, apolipoprotein A-I (apoA-I) and BTN3A1 play a synergistic role causing myeloma cells to secrete supraphysiological levels of IPP, which eventually leads to the exhaustion of Vγ9Vδ2T cells and a decrease in cytotoxicity and other related antitumor effects [70] (Fig. 2).