Fig. 4
From: GRP78 in lung cancer
GRP78 mediates the interaction between lung cancer and tumor microenvironment. When the tumor microenvironment is stimulated by hypoxia, glucose deprivation, low pH, ROS accumulation, and viral infections, the cancer cells experience ER stress and increased GRP78 expression. The adaptive UPR is activated to support the survival, growth, and invasion of tumor cells. In addition, the cancer cells secrete pro-angiogenic factors to stimulate the proliferation of endothelial cells, thereby providing nutritional support for the cancer cells. Also, cancer-related fibroblasts promote the invasion of cancer cells by upregulating GRP78 expression