CD4 and pancreatic neoplasm: Cross-species sequencing of pancreatic tumors in mice and humans has also revealed the existence of another interesting CAF population with the ability to present antigen.36 These antigen-presenting CAFs express both CD74 and major histocompatability complex-II (MHC-II), indicating a propensity to present antigen to CD4+ T cells in vivo, potentially resulting in increased activation of CD4+ T cells.36 The plasticity of these CAF populations and this ‘Jekyll and Hyde’ influence on the immune system present a complicated case for targeting the stroma to mediate immune activation in PDAC.