Second, hair follicle bulge cells, which are multipotent stem cells that support hair follicle cycling and repopulation, might be the cells that give rise to various skin appendage tumors, and the truncated ITF promoter used in this study might be useful to express other cancer-associated exogenous genes specifically in hair follicle bulge stem cells, and further investigate their role in adnexal tumor development. Here, TFF3 is linked to epidermal appendage tumor.