Figure 4.

IGF-dependent and IGF-independent actions of IGFBP-1. The single green headed arrow is activation arrow and red headed arrow is inhibition arrow. (i) The phosphorylated IGFBP-1 has a much higher affinity for IGF-1; therefore, phosphorylation of IGFBP-1 would prevent IGF-1 to interact with its receptor. (ii) The RGD motif of IGFBP-1 interacting with α5/β1-integrin receptors on the cell surface is thought to be the main mechanism by which IGFBP-1 exerts IGF-independent effects, and it could lead to cross-talk with IGF signaling pathways.