We were also able to demonstrate this effect of ATO on NK cells (CD56+CD3−) in vivo by showing an increased expression of CD107a in APL patients (undergoing ATO treatment) when co-cultured with NB4 cells compared to healthy controls (no ATO exposure) (Figure 3B; Figure S3 in Supplementary Material). This evidence concerns the gene NCAM1 and acute promyelocytic leukemia.