To further investigate whether C-FOS is an important downstream target of RUNX1-IT1 and RUNX1, we performed rescue experiments in vitro.The effect of RUNX1-IT1 or RUNX1 on PC cell proliferation, migration and invasion was partially ameliorated by C-FOS knockdown (Fig. 6a–g; Additional file 14: Supplementary Fig. S8a–e). Here, FOS is linked to pachyonychia congenita.