To investigate the role of IFITM3 in B-ALL, patient derived xenograft cells PDX2 were transduced with either a the constitutively membrane associated IFITM3-Y20E mutant or EV control. Additional mutation of PIP3 binding sites within the conserved internal loop region - K83/K104 or R85/R87/K88 - were introduced to test the predicted function of these sites.