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