Using an in vitro approach, in which the transmigration of T cell populations toward supernatants derived from primary cultures of tumor cells derived from patients with head and neck carcinomas, Schmidtner et al. (2009) have demonstrated that supernatants from irradiated cells significantly decrease the transmigration of CD4+CD25highFoxp3+ Treg cells, yet had no effect on the transmigration of CD4+CD25− T cells. Here, CD4 is linked to head and neck carcinoma.