HOXB4, retroviral vectors, and DNA-binding properties of HOXB4 mutants examined. (A) Retroviral vectors and mutant HOXB4 cDNAs. (B) Western blot analyses of the in vitro–transcribed and translated WT and mutated HOXB4 proteins. (C) DNA-binding capacity of HOXB4, HOXB4(N→A), and HOXB4(W→G) proteins. Additions to each binding reaction are indicated above the lanes. Monomeric HOXB4 proteins bound to DNA are denoted by Hox to the left, and an arrow in lane 3. Heterodimers of HOX and PBX are denoted as Hox/Pbx, and by an arrow in lane 4. The position of anti-HOXB4 antibody supershifted complex is denoted by SS to the left, and an arrow in lane 5.