DDIT3 and melanoma: In this study, 4-phenylbutyric acid (4PBA, a chemical chaperone) and small interference RNA (siRNA) knockdown of C/EBP Homologous Protein (CHOP)/growth arrest- and DNA damage-inducible gene 153(GAD153) blocked NPC-402-mediated autophagy induction, thus confirming the role of ER stress and autophagy in melanoma cell death.