PTGDR and pachyonychia congenita: We further investigated the interaction between SOX21-AS1 and SOX21 on PC progression, we up-regulated the level of SOX21 in PC cells (Additional file 1: Figure S1C), and found that SOX21 overexpression reversed the inhibited proliferation property in SOX21-AS1 silenced cells (Additional file 3: Figure S3A, B).