It protects Th2 cells from cytokine deprivation‐induced apoptosis via DP2 signaling,50 and antagonizes PGE2‐mediated Bax activation and hence inhibits the induction of apoptosis in glioma cells.51, 52 In contrast, PGD2 induces apoptosis in human osteoclasts,53 leukemia cells54 and non‐small cell lung carcinoma cell lines.55, 56 In eosinophils, PGD2 has been suggested to decrease the portion of late apoptotic eosinophils at nanomolar concentrations,21 but to induce apoptosis in micromolar concentrations (≥10 μM).26 The gene discussed is PTGDR2; the disease is leukemia.