Figure 4.

Hypoxia activates SHP-1 and SHP-2 in NK cells. (a–c) Western blotting analysis shows SHP-1 and SHP-2 expression in normoxic (20% O₂) and hypoxic (1% O₂) KHYG-1 (a), NK92 (b) cells, and primary NK cells (c), respectively. (d) Western blotting analysis shows the effects of SHP-1 inhibitor TPI-1 on the phosphorylation of ERK and STAT3. Hypoxic KYHG-1 cells were pretreated with 5 μM TPI-1 for 2 h, and then the cells were collected for Western blotting analysis. Representative Western blot images are shown in upper panel; the densitometric analysis is shown in lower panel (n = 3, ^∗P < 0.05, ^∗∗P < 0.01, ^∗∗∗P < 0.001). (e) Flow cytometric analysis of the effects of TPI-1 on the NK cell cytotoxicity. Left panel: representative flow cytometry results of TPI-1 on the cytotoxicity of KHYG-1 cells. KHYG-1 cells were pretreated with 5 μM TPI-1 for 2 h and then incubated with K562 cells at different E : T ratios for 4 h. Right panel: statistical analysis of the effects of TPI-1 on KHYG-1 cell cytotoxicity against K562 cells (n = 3, ^∗P < 0.05).