We became interested in the clinical observations on PCAF expression because we had independently found from performing a functional genomics (shRNA knock-down) screen that loss of PCAF or its binding partner ADA3 resulted in protection of cancer cell lines from a range of apoptotic stimuli such as anti-cancer drugs, UV irradiation and human granzyme B, that operate by inducing MOMP15,17. Here, GZMB is linked to cancer.