... to high-anity recombinant IGF1 R. Binding of IGF -I (A), des-(1±3) -IGF -I (B), Arg3 -IGF -I (C), Gly3 -IGF -I (D), Lon g IGF -I (E), Ala31 -IGF -I (F), Leu 24 -IGF -I (G) and L eu60 -IGF -I (H) to rhIGF1R ... similar to IGF -I. Long Gly3 -IGF -I and Long Arg3 -IGF -I also had similarrhIGF1R-binding af®nities to IGF -I (data not shown).The a nalogues Leu24 -IGF -I, des-(2,3)-Leu24 -IGF -I, Ala31 -IGF -I, des-(2,3)-Ala31 -IGF -I ... [Long IGF -I, des-(1±3) -IGF -I, Arg3 -IGF -I, Gly 3- IGF -I, Arg6 -IGF- II and des(1±6 )IGF- II] have basicallyequal abilities to prevent apoptosis. Conversely, IGF -I analogues with d isrupted IGF1 R binding...