ERN1 and melanoma: The HA15 compound, a BiP inhibitor, has been observed to induce cell death and autophagy tested in melanoma models 289 Further UPR‐activating compounds have been identified, including IXA4 (an IRE1α–XBP1s activator), MK‐28 (a PERK activator), and AA147 (an ATF6 activator),290 but their antitumor activity in vivo has yet to be fully defined.