AREG and pachyonychia congenita: To identify the expression levels of AREG in PC tissues, we first assessed AREG expression in PC tissues using the GEPIA database (http://gepia.cancer-pku.cn/) and observed that AREG mRNA levels were markedly upregulated in PC tissues (T = 179) when compared to adjacent normal tissues (N = 171) (Fig. 1B), and high AREG expression was related to poor prognosis (Fig. 1C).