PTEN and breast neoplasm: Consistent with the hypothesis that PI3Kβ has an important role in promoting the growth of PTEN-null tumours, AZD8186 inhibited the growth of the PTEN-null tumour xenograft models 786-0 (renal cell line) and U87-MG (glioma), but did not inhibit the PIK3CA/PI3Kα mutant breast tumour xenograft model BT474C (Fig. 1a–c).