IL2RG and severe combined immunodeficiency: To ensure successful engraftment and prevent immune rejection, human cSCC cells are typically inoculated into immunodeficient murine hosts, such as the T-cell-deficient athymic Nude (nu/nu) mice, the T- and B cell–deficient severe combined immune deficiency (SCID), or the extremely immunocompromised NSG [NOD/SCID/IL2 receptor gamma chain (IL2Rγ)-null] and NOG (NOD/Shi-SCID/IL2Rγ-null) mouse strains, which lack mature T cells, B cells, and NK cells, and have dysfunctional macrophages and dendritic cells (176).