However, the functional relevance of up-regulated keratinocyte membrane FasL, and thus its ability to induce keratinocyte cell death, has been questioned by some as the above ex-vivo demonstration of the lytic ability of keratinocyte FasL in TEN was limited in its effect on lymphoid target cells and not demonstrated with keratinocytes as target cells. The gene discussed is FASLG; the disease is toxic epidermal necrolysis.