CD44 and pachyonychia congenita: Jiang et al. revealed that activation of Snail1 upon CD44 overexpression induces a mesenchymal phenotype and regulates the invasive capabilities of the PC cells via membrane-bound metalloproteinase (MMP-14/MT1-MMP) expression, thus establishing the key regulatory effect of CD44-Snail-MMP axis in the EMT program and invasion in PC [110].