CD274 and acute myeloid leukemia: Thus, VLA-4 activity and PD-L1 expression were both inhibited by SAS and AS101 in malignant cells, as shown in Figure 1 and Figure S2A and B. In addition, in contrast to human AML cell lines, which expressed high levels of VLA-4 and PD-L1 (Fig. 1B), isolated primary AML cells that did not express VLA-4 also lacked PD-L1 expression (Fig. 2C), suggesting a possible association between the expression of these two proteins.