In accordance with previous results in a large panel of breast tumor cell lines [6], while PI3K mutational status was also predictive of sensitivity to GDC-00941 in the more diverse NCI-60 panel, PI3K mutational status was not 100% specific for prediction of sensitivity, suggesting a more complex relationship between PI3K activation and de novo sensitivity to GDC-0941. The gene discussed is PIK3CA; the disease is breast neoplasm.