This model was based on the ability of antibodies against unknown IFITM1 external epitopes to aggregate leukaemia cells [15], [17], immunoprecipitation of extracellular radiolabelled IFITM1 [18] and the accessibility of IFITM3 NTD and CTD epitope tags at the cell surface by FACS and immunofluorescence assays, respectively [1]. Here, IFITM1 is linked to leukemia.