In this regard, further in the work, to assess the possibility of overcoming the resistance of THP-1 AML cells in high-density cultures, we used a low-molecular-weight inhibitor of Bcl-2 family proteins (Bcl-2, Bcl-w and Bcl-xL)—BH3 mimetic Navitoclax (ABT-263). This evidence concerns the gene BCL2L1 and acute myeloid leukemia.