Fig. 4

CD97 mediates mechanotransduction in osteoclast differentiation. a Representative tartrate-resistant acid phosphatase (TRAP) staining of osteoclasts in control or CD97 knockdown RAW264.7 cells cultured with or without static compression. The osteoclasts are highlighted by black dotted lines. Scale bar, 100 μm. b Quantification of the number of osteoclasts. c Representative scanning electron microscopy (SEM) images of resorption lacunae on bovine bone slices in control or CD97 knockdown RAW264.7 cells cultured with or without static compression. Resorption lacunae are indicated by white tringles. The white box area indicates a higher magnification. Scale bar, 500 μm. d Quantification of the number of resorption pits. e Representative podosome actin belt of osteoclasts with fluorescein isothiocyanate (FITC)-phalloidin staining and nuclei stained with DAPI. Scale bar, 100 μm. f Quantitative analysis of podosome actin belt size. g–j Quantitative real-time polymerase chain reaction (qRT‒PCR) analysis of the osteoclast differentiation-related genes in control or CD97 knockdown RAW264.7 cells cultured with or without static compression. Values are expressed as the mean ± SD. P values were calculated using two-way analysis of variance (ANOVA) with Tukey’s post hoc test. *P < 0.05, **P < 0.01, ***P < 0.001