Although the mechanisms underlying MC degranulation at the interface with HPV16 E7 epithelium are yet to be fully understood, production of ET-1 by the virus affected epithelium [43] or by the surrounding microenvironment in E7 transgenic mouse skin (Fig. S4), and the ability of this peptide to promote tumor invasion [44] as well as induce MC degranulation [25] represents a potential means of MC activation in our current study. The gene discussed is EDN1; the disease is neoplasm.