FIG. 1.

Synthetic ligands for ErbB dimerization. The ligand-binding domains FKBP12 and FRB (A) were subcloned as single or double copies to generate the expression vectors shown in panel B. The intracellular domains of ErbB receptors were PCR amplified and subcloned into the expression vectors as described in Materials and Methods. The addition of AP1510 to cells expressing FKBP-fused ErbB receptors (C) will result in the generation of homodimers (D), while the addition of rapamycin to cells coexpressing the ErbB1-FKBP chimera (p75.B1.F1.HA) and ErbB2-FRB chimera (p75.B2.R1.Flag) will result in a p75.B1.F1.HA-p75.B2.R1.Flag heterodimer (D).