CD300 functional behavior is modified based on complex composition. A, CD300 receptors (Myc or HA-tagged) stably transfected on RBL-2H3 cell surface were assessed by flow cytometry using anti-Myc9E10 (light gray histograms) and anti-HA12CA5 mAb (dark gray histograms). Isotypic mAb was used as negative control (black histograms). B and C, RBL-2H3 transfectants were transiently transfected with 3×NFAT/AP1-Luciferase and TK-Renilla plasmids. Luciferase activity was measured after stimulation for 7 h with the indicated antibodies. Data are normalized as described before. Duplicates were performed for all stimulations. Results are representative of three and two independent experiments respectively (*, p ≤ 0.05; **, p ≤ 0.01). N.S., non-significant. Error bars represent standard deviation.