Figure 4: Overexpression of PK2 and GC-2 apoptosis. GC-2 cells were either transfected with various concentrations of the pCMV-HA-PK2 plasmid (4 μg and 8 μg), or empty vector plasmid for 48 h as a control. (a) The apoptosis rate was quantified by flow cytometry of GC-2 cells labeled with Annexin V-FITC and PI. (b) Cell viability in the different groups with various concentrations of plasmid was determined by CCK8 assay. (c) The cell lysates were analyzed by Western blotting with antibodies against cleaved-caspase-3, caspase-8, Bax, and Bcl-2. (d) The concentrations of intracellular calcium of GC-2 cells were determined by immunofluorescence. The scale bars represent 100 μm. All experiments were replicated in three independent experiments from different cell samples. Con: the cells were transfected with an empty vector. Each treatment group was compared with the control group, **P < 0.01 (one-way ANOVA). PK2: prokineticin 2; Bax: B cell lymphoma 2-associated X; Bcl-2: B cell lymphoma 2; ANOVA: analysis of variance.