The endoplasmic reticulum is susceptible to various stresses that provoke the accumulation of unfolded proteins in it, inducing stress response in cells, and altering the growth and function of cells. This is the endoplasmic reticulum stress（ERS）. ERS will happen in chondrocytes, the only cells in cartilage, after exposing to glucose deprivation, interleukin-1β, nitric oxide and some drugs. ERS triggers an evolutionarily conserved series of signal transduction events, which constitutes the unfolded protein response（UPR）. The three major transducers of the UPR are inositol-requiring（IRE）1, protein kinase R-like endoplasmic reticulum kinase（PERK）, and activating transcription factor（ATF）6. They trigger major signal pathways of UPR, which affect the growth, apoptosis of chondrocytes and the inflammation of cartilage. Advances in the research into ERS, PERK, IRE1 and ATF6 signal pathways are reviewed in this article.
