ACP5 and prostate cancer: Importantly, the fraction of bone lined by RUNX2- and TRAP-positive cells, respectively, varied in between samples, but was significantly correlated within samples (Rs = 0.67, p = 0.000009, n = 35) (Figure 2), supporting results from the PCA analysis and indicating parallel activation of osteoclasts and osteoblasts in prostate cancer bone metastasis.