Qian et al. found that mice bearing 4T1 breast tumour cells have an increased number of Th17 cells not only in tumour tissues but also in the spleen and peripheral blood and that this is due to PGE2 secreted from the tumour, which induces IL‐23 in DCs through EP2/EP4 receptors and a CREB‐dependent manner (Qian et al., 2013). The gene discussed is CREB1; the disease is neoplasm.