GFAP and tarsal-carpal coalition syndrome: In order to further observe the distribution and cellular localization of S1PR1 in the TCC area, we co-stained S1PR1 with Iba1(Ionized calcium-binding adaptor molecule, a microglia marker), GFAP (Glial fibrillary acidic protein, an astrocyte marker), and NeuN (Neuronal nuclei, a neuronal marker) in the NTG group.