X-ray co-crystal structure of the small molecule inhibitor GDC-0941 bound to human PI3 kinase gamma isoform (PDB code 3dbs). The image shows the drug bound in the ATP binding pocket of the kinase. GDC-0941, now in Phase I clinical trial, was evolved from the earlier inhibitors PI-103, PI-540, and PI-620, as described by Raynaud, Workman and colleagues in this issue. The authors thank Drs Rob Van Montfort and Isaac Westwood, Sections of Cancer Therapeutics and Structural Biology, The Institute of Cancer Research (ICR), for the expert preparation of the image, which was made with the program CCP4MG. For details, see the article by Raynaud and colleagues 1725.