In addition, Dong and Zhang et al. indicated that there are differences in the expression of PDE4D in hematological malignancies, i.e., compared to peripheral blood mononuclear cells from healthy adults, the expression of PDE4D is significantly reduced in cells extracted from patients with chronic lymphocytic leukemia, while is more abundant in CEM and Jurkat T leukemia cell lines [6,7]. This evidence concerns the gene PDE4D and leukemia.