HSP90B1 and ovarian carcinoma: Also in this setting, DDIT3, HSPA5, HSP90B1, ATF6, and XBP1 levels exhibited a highly significant positive correlation with CALR expression (Fig. 2c), corroborating the notion that ovarian cancer cells are subjected to ER stress irrespective of treatment, resulting in spontaneous CALR upregulation in a majority of patients.