Expression in hepatomas and chromosomal localization of rat protein phosphatase 5 gene.

The serine/threonine protein phosphatase type 5 (PP5) gene expression was ubiquitously observed among all the tissues examined, but being at the lowest level in the liver. The levels of PP5 mRNA were markedly elevated in rat highly malignant ascites hepatomas, while those in several rat primary hepatomas were slightly increased and those in the regenerating livers were not elevated at all compared to the control liver. The PP5 gene was mapped to rat chromosome 1q22.1. This region has been identified to have linkage homology among human, mouse and rat, and is known to be associated with several tumor types. Taken together, the present results strongly suggest important roles of PP5 in tumorigenesis.