(A) Constructed plasmids were transfected into 293T cells. The interactions of TREM2 with SHP1, SHP2, and SHIP1 were determined by co-IP and Western blot 48 hours later. (B) PMφ cells were stimulated with LPS (1 μg/ml) for 12 hours and immunoprecipitated with IgG or TREM2 Ab to determine the binding between TREM2 and SHP1. (C) WT and TREM2^–/– PMφ cells were stimulated with LPS (1 μg/ml) for indicated times. The phosphorylation and total levels of SHP1 were determined by Western blot. (D) TREM2 plasmid was transfected into BMDMs. Forty-eight hours later, BMDMs were pretreated with PTP inhibitor II (1 μM) or NSC87877 (1 μM) for 1 hour, followed by the treatment of LPS (1 μg/ml). BTK phosphorylation was assessed 12 hours later. (E) TREM2, SHP1, and DAP12 plasmids were transfected into 293T cells. Forty-eight hours later, co-IP assay was performed to determine the interaction between TREM2 and SHP1. (F) WT and DAP12-deficient (DAP12^–/–) pMφ cells were treated with LPS (1μg/ml) for 12 hours and immunoprecipitated with IgG or TREM2 Abs. The binding among TREM2, DAP12, and SHP1 was detected by Western blot. (G) Plasmids expressing TREM2 lacking extracellular domain (ΔExtra) or transmembrane plus cytoplasmic domain (ΔTrans-cyto) and expressing SHP1 were transfected into 293T cells. Forty-eight hours after transfection, co-IP was performed. (H) TREM2 plasmid was transfected into 293T cells with full-length SHP1, N terminal-SH2 domain (N-SH), C-terminal SH2 (C-SH), or PTPase domain of SHP1, respectively, and the interactions of TREM2 with these domains were determined by co-IP after 48 hours. (I) PTPase domain or PTPase domain containing R352A, K356A, R358A, N359A, Y536A, or Y564A mutations were transfected into 293T cells with TREM2 plasmid and the interactions were determined 48 hours after transfection.