To evaluate the sGRP78‐releasing capacity induced by various therapeutics, the breast cancer cell line E0771 was engineered to express GRP78‐mCherry (mCherry was fused to GRP78 via a flexible linker to prevent interference with GRP78 function, as shown in Figure S2A, Supporting Information) and then exposed to chemotherapeutics. Here, HSPA5 is linked to breast carcinoma.