St. Jude Children’s Research Hospital、Loyoba大学和京都大学的研究人员发现用来调节新蛋白折叠的部分分子机制还包含一种遗传性反应，这个反应能够扩大蛋白质折叠和包装的工厂（内质网）。研究人员将这些发现公布在2004年10月15日的Journal of Cell Biology（JCB）上。
蛋白质折叠工厂（内质网）的构建之间的这种关连能够确保这两个过程在细胞需要快速制造、折叠和分泌大量特定蛋白时能协调运作。
研究人员发现细胞会产生一种叫做XBP1的分子以满足蛋白质折叠机器不断增长的需要。这种对折叠蛋白需求的增长会导致所谓的未折叠蛋白反应（UPR）以及蛋白质折叠和包装的工厂的膨胀。UPR还能促进细胞产生分子伴侣。
XBP1能够引发细胞产生卵磷脂。卵磷脂是构成内质网（ER）的重要建筑材料。ER中的膜能充当包装已折叠蛋白的包膜。当离开ER后，这个包膜就会融合到细胞膜内侧。一旦融入细胞膜，包膜就会打开并将其内的蛋白质放出细胞外。
通过将分子伴侣的制造和卵磷脂的合成联系起来，XBP1能够协调新ER的构建和装备并以此提高细胞折叠和运送蛋白的能力。
研究人员通过对是小鼠的纤维原细胞的研究发现了这个机制。他们将XBP1基因插入一种病毒并利用这种转基因病毒将这种基因引入纤维原细胞内。XBP1基因使纤维原细胞膜产生有关的关键酶类的活性明显增加。因为，已经知道UPR能够活化XBP1基因，所以这项研究表明XBP1能够将ER的膨胀和增加折叠和包装分泌性蛋白的能力联系在一起。
这项研究解释了细胞能够快速满足增加特定蛋白产量需求的原因，即通过折叠和装配蛋白任务的协同来达成这种任务。而且，这些发现也促进了人们对细胞生物学的进一步了解。
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