Fig. 6. OLIG proteins co-localize and interact with ID2 and ID4 in neural progenitor cells. (A) E17 neural progenitor cells were grown for 7 days in the presence of 10 ng/ml EGF (parts a,d), 3 days with 10 ng/ml PDGF-AA+NT3+EGF (parts b,e) and 12 hours with 20 ng/ml BMP4 (parts c,f-h). Cells were plated and stained for OLIG1 and ID2 (part g), OLIG1 and ID4 (part h), OLIG2 and ID2 (parts a-c) and OLIG2 and ID4 (parts d-f). Nuclei were counterstained with DAPI. In the absence of BMP4, both OLIG1 and OLIG2 were localized primarily in the nucleus. However, after BMP4 treatment both OLIG1 and OLIG2 were colocalized with ID2 and ID4 in the cytoplasm. (B,C) Co-immunoprecipitations were done with protein lysates from cultured E17 neural progenitor cells treated with BMP4 for 12 hours. OLIG1 (B) and OLIG2 (C) interact with both ID2 and ID4.