It was found that IGF-1 involvement does not only promote proliferation but also cell growth via directly activating specific trans-membrane tyrosine kinase receptors that are primarily overexpressed in BC, resulting in the up-regulation of the insulin receptor-substrate-2 (IRS2) and causing a downstream activation in the in PI3K-Akt and MAPKinase pathways [9]. Here, IRS2 is linked to breast cancer.