A study examining the expression level of leptin, which causes increased breast cancer development showed that it accelerates the PC process by activating the Notch signaling pathway associated with tumor metastasis and CSC differentiation in BxPC-3, MiaPaCa-2, Panc-1 and AsPC-1 PC cells (Ramakrishnan et al., 2011). Here, LEP is linked to pachyonychia congenita.