BST1 and acute myeloid leukemia: To pinpoint the emerging role of CD157 in AML, we generated stable CD157 knockdown versions from the parental U937, THP1 and OCI-AML3 cell lines using lentiviral vectors expressing two shRNA (shCD157#1 and shCD157#2) targeting CD157 or a scramble control sequence that conserved endogenous expression of CD157 (CD157high cells).