Sex differences are markedly evident in many types of cancer, and one of the major contributors to sex-biased differences lies in the sex chromosomes. In contrast to the traditional view that Y chromosome-encoded proteins only function in male reproductive organs, recent evidence suggests that select Y chromosome-encoded proteins are also expressed in male non-reproductive tissues. Furthermore, dysregulation of the Y chromosome-encoded proteins has been implicated in cancers in non-reproductive organs. Upon closer examination, this subgroup of Y chromosome proteins each has corresponding proteins on the X chromosome. Dr. Liu will study the function of the Y chromosome-encoded proteins and whether and how protein sequence differences from their X chromosome-encoded counterparts lead to functional distinctions in cancer development.