...generally greater sensitivity to the selective PI3K inhibitor GDC-0941 in epithelial compared with mesenchymal cell lines (P < 0.04, Fig. 4A); 4 of the 6 least sensitive epithelial cell lines harbored RAS mutations, whereas the 2 most sensitive mesenchymal lines harbored PIK3CA mutations (Fig. 4A and B). In addition, cell lines with receptor tyrosine kinase (RTK), PIK3CA alterations, or PTEN loss were significantly more sensitive to GDC-0941 as a class...