IL4R mutations in nm-PMBLsig⁺ tumors induce JAK-STAT activation. (A) Mutational pattern of IL4R (UniProtKB-P24394) in nm-PMBLsig⁺ tumors (top) and other DLBCL tumors (bottom) from the BCC cohort specified according to receptor domains (extracellular, transmembrane, or cytoplasmic). Colors and shapes of lollipops represent the DLBCL90 NanoString assay tiered classification of samples (see Figure 1) and type of mutation (circle, missense or in-frame indel; diamond, truncating), respectively. The plot was created using R package TrackViewer (version 1.24.0). (B-G) Ectopic expression of WT IL4R and mutants in HEK Blue IL-4/IL-13 (Invivogen) (B-C) and DEV cells (D-G). (B) Quantification of pSTAT6-dependent expression of secreted embryonic alkaline phosphatase (SEAP) in supernatant. (C-D) Immunoblot for pSTAT6, STAT6, IL4R, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). (E-F) CCL17 and CD23 messenger RNA expression measured by quantitative polymerase chain reaction. (G) IL4R surface expression measured by flow cytometry. Data are means ± standard deviation of 5, 4, 7, and 7 experiments in panels A, E, F, and G, respectively; significance was evaluated using a 1-sample Student t test. *P < .05, **P < .01, ****P < .0001.