IRS1 and melanoma: NT157, the small molecule IRS1/2 inhibitor, developed by Dr. Alexander Levitzki, functions by serine phosphorylation and destruction of IRS-1 and IRS-2, leading to long-term blocking of IGF-1R signaling and strong inhibition of tumor growth [14] in ovarian and prostate cancers as well as BRAF inhibitor-resistant melanoma [15].