Insulin-like growth factors signaling through the type IGF receptor (IGF1R) regulate proliferation, metastasis, and metabolism of breast cancers. In triple negative breast cancer (TNBC) IGF1R regulates metastasis. In TNBC, inhibition of IGF1R blocks metastasis but not tumor growth at the primary site. In ER+ cell lines IGF-I regulates tumor growth in the primary site. Drugs targeting IGF1R are being tested in clinical trials but no biomarkers of IGF driven tumors have been identified. This project seeks to develop an IGF driven metastasis signature in triple negative breast cancers that could potentially be used to identify patients with TNBC that may benefit from inhibition of the IGF system. To generate the signature two TNBC cell lines and one ER+ line were treated with the ligand IGF-I, an inhibitory Ab, or IGF-I and antibody together for 4 and 24h. RNA was isolated and samples were subjected to RNA sequencing using 100 bp paired end runs on the HiSeq 2000 through the University of Minnesota Genomics Center.