CD8A and neoplasm: Furthermore, virus-, tumor-, or alloantigen-specific CD8+ TRM cells deficient in CD103 expression show impaired persistence in the brain, lung and the intestinal epithelium (El-Asady et al., 2005; Masson et al., 2007; Wakim et al., 2010; Lee et al., 2011; Casey et al., 2012).