CD40 and diffuse large B-cell lymphoma: Burington et al (Burington, B., Yue, P., Shi, X., et al: CD40 Pathway Activation Status Predicts the Anti-Tumor Activity of CD40 Therapy in Diffuse Large B-Cell Lymphoma, submitted) hypothesize that dacetuzumab sensitivity in tumor B-cells is associated with an inactive CD40 pathway, which in turn is characteristic of normal germinal center B-cells, while the CD40 pathway in normal activated B-cells is active.