ATF4 and melanoma: It has been demonstrated that δ-TT triggers cell death and activates ER stress-related pathways such as PERK/p-eIF2α/ATF4/CHOP and IRE1α to induce apoptosis in melanoma cells and that δ-TT significantly inhibits tumor growth rate in A375 melanoma animal model (Montagnani et al., 2016).