Molecular chaperones are a broad class of proteins that assist with the folding or assembly of other structures. A subfamily of chaperones are heat shock proteins, highly conserved and ubiquitous, and function in protection from thermal and oxidative stresses. Some notable members include HSP60, HSP70, and clusterin or apolipoprotein J. Hsp60 is mitochondrial and is involved with proper folding of imported proteins. Hsp70 binds to hydrophobic residues from stressed and partially unfolded proteins, allowing them to refold. It is also known to directly inhibit apoptosis by blocking the recruitment of procaspase-9 to the apoptosome. Clusterin is a Golgi chaperone whose overexpression has been observed to protect the cells from apoptosis. Antibodies against specific chaperone proteins can serve as useful tools in their respective processes.