Because phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is the major negative regulator of AKT phosphorylation, we also examined its levels in WT and B7-H4-null AML cells, and showed that PTEN was markedly downregulated in B7-H4-null leukemia cells (Figure 5c, first panel). The gene discussed is AKT1; the disease is acute myeloid leukemia.