Topo IIα and Metnase are expressed and interact in blood cells. (A) Western blot of multiple acute leukemia cell lines and normal CD34⁺ hematopoietic progenitors to show expression of Metnase and Topo IIα. HEK-293T cells do not express Metnase by virtue of their transformation by T antigen. They serve as a control for these studies. (B) Metnase and Topo IIα coimmunoprecipitated with each other from THP-1 AML cells in the presence of DNase I, indicating that their interaction is independent of DNA. (C) Metnase shRNA reduces Metnase mRNA in THP-1 AML cells as shown by RT-PCR. (D) Metnase shRNA reduces the expression of Metnase protein in THP-1 cells as shown by Western analysis.