Xbp1-GFP reporter assay in response to ER stress

To detect the UPR signaling induced by ER stress accumulation in wing imaginal discs, we observed expression of Xbp1-GFP generated as a consequence of ER stress-induced splicing of the mRNA transcribed from UAS-Xbp1.EGFP.LG. Wing imaginal discs were dissected from matured third-instar larvae in 0.7% NaCl. The living discs were observed without fixation and observed under a conventional fluorescent microscope (IX81, Olympus, Tokyo, Japan,).