A Twenty-First Century Cancer Epidemic Caused by Obesity: The Involvement of Insulin, Diabetes, and Insulin-Like Growth Factors

Table 3

Affinities of insulin, IGF-1, and IGF-2 for homodimers and heterodimers of isoform A (IR-A) and isoform B (IR-B) of the insulin receptor and type I IGF receptor (IGF-IR).

Ligand	IR-B : IR-B	IR-A : IR-A	IR-A : IR-B	IGF-IR : IGF-IR	IGF-IR : IR-B	IGF-IR : IR-A
Insulin	0.5 nM^$	0.25 nM	0.5 nM	100 nM	80 nM	70 nM*
IGF-1	100 nM	10 nM	40 nM	0.2 nM	0.3 nM	0.4 nM
IGF-2	10 nM	2 nM	10 nM	0.5 nM	0.5 nM	0.7 nM

$Affinities are taken from or are estimated from the different relative affinities reported in [92, 100–102, 104, 310]. *The affinities reported for the hybrid between type I IGF receptor and isoform A of the insulin receptor are discrepant.