IGF1 and cancer: It was further shown that in some cases, including a large percentage of human non-small cell lung cancers, AKT activity can be low despite loss of PTEN; in an experimental setting, such cancers were sensitive to upstream activation by insulin and IGF-1, and regressed during CR.68 Other common mutations in oncogenes such as RAS and BRAF or tumor suppressors such as TP53 did not affect the sensitivity of such tumor cells to insulin and IGF-1 in vitro or to CR in vivo.