TEL-PDGFRβ and FIP1L1-PDGFRα constructs. Constructs used in this study, cloned in retroviral vectors MSCV-IRES-EGFP (enhanced green fluorescent protein), MSCV-neomycin, or MSCV-puromycin as indicated in “Materials and methods.” PNT indicates the pointed domain in TEL that mediates dimerization of the fusion protein; TK, the tyrosine kinase domains.