Activation/phosphorylation of Erk. Level of phosphorylated Erk (pERK) detected at time points: 1, 3, 6, 24, 48 h in cell cultures of guinea pig primary gastric epithelial cells (A) or fibroblasts (B), not transfected or transfected with siRNA IL-33, in medium only or exposed to H. pylori glycine acid extract. (GE). Activation of Erk was estimated based on relative fluorescence units (RFU) of cells intracellularly stained for pErk. Fluorescence was measured in a fluorescence reader (Victor 2, Wallac, Oy Turku, Finland) at wavelength: 495 excitation and 519 emission (emission). The results of four independent experiments performed in triplicates for each experimental variant are presented. Statistical analysis was performed using the nonparametric U Mann-Whitney test with significance for *, ** p < 0.05, * unstimulated (only medium) vs. GE stimulated untransfected or transfected cells, ** untransfected vs. transfected cells in medium only or in medium with GE.