TIE2 receptor expression by TIE2⁺ monocytes. (A) TaqMan analyses of TIE2 and VEGFR2 transcripts in FACS-sorted monocyte subsets showing ΔCt values over endogenous control GAPDH. The lower the ΔCt, the higher the expression of the transcript in the target cell population. ΔCt values are expressed as mean ± standard error. Note that TIE2 transcript is clearly expressed in CD14^lowCD16⁺ (14^low16⁺) resident but nearly undetectable in CD14⁺CD16⁻ (14 ⁺16⁻) inflammatory monocytes. (B) Relative quantification values of TIE2 transcript in FACS-sorted monocyte subsets. TIE2 transcript is significantly enriched in CD14⁺TIE2⁺ (14⁺TIE2⁺) TEMs compared with the resident monocytes. For each relative value, an interval of confidence was calculated; confidence intervals that do not overlap indicate statistically significant differences (P < .05). (C) Western-blot analysis of TIE2 protein expression in the indicated cell populations. Blots were probed with C-terminus specific anti-TIE2 rabbit (top panels) or mouse anti-β actin (bottom panels) antibodies. The expected migration of each protein relative to molecular weight standards is indicated. Representative experiment of 3 performed. (D) TIE2 immunoprecipitated from CD14^lowCD16⁺ resident monocytes is phosphorylated on tyrosine. Representative experiment of 2 performed.