DLL1 and acute lymphoblastic leukemia: Indeed, consistent with the PHF6-mediated regulation of NOTCH1 expression in B-ALL cells (Meacham et al., 2015), we also observed reduced NOTCH1 expression upon stable PHF6 knockdown in Jurkat leukemic T cells, as well as in OP9-DLL1 cocultured human CD34+ HPCs (Figure 4B).