FOXO1 and sarcopenia: Comparisons are challenging, however, because the definitions of sarcopenia were not the same, conventional definition for Chen et al. and Asian Working Group for Sarcopenia (AWGS) for the three others and the quantification techniques were different, SYBGreen for He et al. and locked nucleic acid (LNA) probe for Liu et al. in plasma and serum for Chen et al. It could be noticed that hsa-miRNA-21 targets Forkhead box protein O1 (FoxO1) and phosphatase and TENsin homolog (PTEN), two genes involved in sarcopenia dysregulation [63, 64].