FLT3-JM-PM receptors are constitutively autophosphorylated on tyrosine residues. (A) Lysates of FL-stimulated (100 ng FL /mL for 5 minutes) and unstimulated, serum-starved FLT3-WT-expressing cells, FLT3-JM-PM-expressing cells (FLT3-V592A, FLT3-V579A, FLT3-F594L, and FLT3-F590GY591D), and FLT3-W51-expressing cells were subjected to immunoprecipitation with FLT3 antibody followed by immunoblotting with phospho-tyrosine antibody. Blots were stripped and reblotted with FLT3-antibody. (B) FLT3-ITD-expressing cells (W51, NPOS, and W78) and FLT3-TKD-expressing cells (D835Y and D835V) were analyzed as described in panel A and densitometric analysis was performed using TINA 2.0 software to quantify the percentage of phospho-FLT3 of total FLT3.