HUCMSC-EXOs promote GC-treated hBMSC osteogenesis by activating PI3K/AKT signaling pathway in vitro. (A and B) Identification of the underlying correlation between PI3K/AKT signaling pathway and osteogenic differentiation using western blotting. (C–K) Quantitative analysis of Western blotting images using ImageJ. (L) Alkaline phosphatase (ALP) activity assay staining (scale bar 500 μm). (M) Relative ALP-positive area as calculated by ImageJ. (N) Alizarin red staining (scale bar 500 μm). (O) Relative Alizarin red-positive area as calculated by ImageJ. (P) p-AKT (Ser 473) expression detection using immunofluorescence. (Q) Quantitative analysis of immunofluorescence by ImageJ.