Klaus Okkenhaug, PhD from Babraham Institute, Cambridge, UK discusses the importance of PI3 kinase, specifically the delta isoform in chronic lymphocytic lymphoma (CLL) and indolent non hodgkin's lymphoma (NHL). PI3 kinase delta is selectively expressed in immune cells and is particularly involved in the activation and differentiation of B-cells. It is a target for the drug idelalisib, and works by interfering in the B-cell receptor signalling pathway or signaling downstream of chemokine receptors. However, patients treated with idelalisib have shown adverse effects, commonly colitis. Recorded at the European Hematology Association (EHA) 2016 Annual Congress in Copenhagen, Denmark.