It is notable that although tumorigenic functions of XBP1-u, besides promoting tumor cell proliferation through suppression of tumor suppressors, have not been reported, it is highly probable that XBP1-u is also involved in the regulation of oncogenes and other hallmarks of cancer, as it can modulate post-translational regulation, including phosphorylation and ubiquitination, which are crucial for regulating the activity and stability of a large number of proteins. This evidence concerns the gene XBP1 and neoplasm.