As a calcium-binding protein in the endoplasmic reticulum, HSPA5 directly inhibits the activation of proapoptotic tissue components under stressful conditions and diverts folded proteins that accumulate in the endoplasmic reticulum to maintain cellular protein synthesis, thereby maintaining calcium homeostasis and the stability of the endoplasmic reticulum of tumor cells. This evidence concerns the gene HSPA5 and neoplasm.