HSPB1 (heat shock protein beta-1, HSP27, HSP28, CMT2F, Hsp25) is a chaperone protein of the sHsp (small heat shock protein) family that protects against oxidative stress. It is overexpressed during oxidative stress to reduce BAX activation and H2O2-induced autophagy and apoptosis within the injured cell. HSPB1 translocates from the cytoplasm to the nucleus upon stress induction. It is generally involved in chaperone activity, thermotolerance, cell survival and inhibition of apoptosis, regulation of cell development and differentiation, and signal transduction. It is overexpressed in various cancers, including hepatocellular, gastric, colorectal, lung and breast carcinomas, and it is associated with a poor prognosis by protecting cells from agents that normally induce apoptosis. Mutated HSPB1 is also causative for Charcot-Marie-Tooth neuropathy and is associated with distal hereditary motor neuropathy. Alternatively, upregulation of wild-type HSPB1 is thought to protect against some of the negative effects of neurodegenerative diseases including Alzheimer’s and Parkinson’s disease. In normal tissues, it is expressed in the cytoplasm with some nuclear positivity in muscle cells and squamous epithelial cells throughout the body. References: Cellular Signalling. 2014. 26 (7): 1616–25, PMID: 24686082; International Journal of Clinical Chemistry. 2013. 417: 73–9, PMID: 23266770; Cellular and Molecular Life Sciences. 2005. 62 (6): 670–84, PMID: 15770419; Journal of Neuroscience. 2011. 31 (43) 15320-15328; DOI: 10.1523/JNEUROSCI.3266-11.2011; PlosOne 2015 doi.org/10.1371/journal.pone.0126229; Nature Scientific Reports 2018 8:688; Neurology 2008 doi.org/10.1212/01.wnl.0000319696.14225.67; Curr Drug Targets 2014 15(4):423-31.