IGF1 and amyotrophic lateral sclerosis: The IGF1/IGFBP binary complex, which adopts similar global folds with the IGF1/IGFBP4 (NBP4/CBP4) complex, binds to the concave surface of ALS through the IGF1 C-domain loop and the IGFBP ɑ3 helix and C-terminal loop.