Fig. 3

Effects of NK2 on NK1-mediated Ca²⁺ influx and ERK phosphorylation. A Optimal concentrations of tachykinin-stimulated Ca²⁺ responses were determined from dose–response curves. HEK293 cells expressing Ca²⁺ probes with NKs were treated with 0.1 nM SP or NKA. The concentration of SP at 0.1 nM was the concentration that fully stimulated NK1 but not NK2. The concentration of NK at 0.1 nM was the concentration that fully activated both receptors. B Effect of SP pretreatment on NKA-stimulated Ca²⁺ responses. Cells expressing Ca²⁺ probes with NKs were treated with 0.1 nM SP for 30 min. Medium was then replaced and 0.1 nM NKA was added. C HEK293 cells and exogenous NK2-expressing cells were serum-starved for 24 h and treated with 0.1 nM peptides. Cells were harvested at designated time point and subjected to western blotting with anti-ERK or phospho-ERK antibodies