MMP-9 has been shown to act through activation of EGFR signaling, and both EGF and EGFR were found to be overexpressed in PCs.[27] Another study corroborated the association between the EGF pathway and MMP-9 by demonstrating that EGFR signaling downstream of EGF regulated MMP-9 secretion and promoted the migration and invasion of human ameloblastoma cells.[28] These data suggest the potential of synthetic MMP-9 inhibitors in PC treatment. Here, MMP9 is linked to pachyonychia congenita.