PCNA and osteoporosis: Tang et al. (2020) showed that cytoplasmic PCNA is involved in osteoclast differentiation in osteoporosis. In addition, the kidneys of high-phosphate diet mice showed higher PCNA expression, macrophage infiltration, and fibrosis (Duayer et al., 2021). Further functional enrichment analysis revealed that these cells with different differentiation directions had specific functions in regulating cell adhesion and organization of the ECM (Figures 4D, E).