Our previous studies demonstrated that the C-terminal acidic domain (CAD) of TSPX is critical for its tumor suppressor functions, such as suppression of cyclin B/CDK1 phosphorylation activities [28], degradation of a HBV viral oncoprotein HBx [34], and inhibition of the androgen receptor (AR) transactivation [22]. Here, CDK1 is linked to neoplasm.