Methods of inhibiting phosphatidylinositol 3-kinase delta isoform (PI3K delta ) activity, and methods of treating diseases, such as disorders of immunity and inflammation, in which PI3K delta plays a role in leukocyte function are disclosed. Preferably, the methods employ active agents that selectively inhibit PI3K delta , while not significantly inhibiting activity of other PI3K isoforms. Compounds are provided that inhibit PI3K delta activity, including compounds that selectively inhibit PI3K delta activity. Methods of using PI3K delta inhibitory compounds to inhibit cancer cell growth or proliferation are also provided. Accordingly, the invention provides methods of using PI3K delta inhibitory compounds to inhibit PI3K delta-mediated processes in vitro and in vivo.
