Paladin (X99384) is expressed in the vasculature and shifts from endothelial to vascular smooth muscle cells during mouse development.

Angiogenesis is implicated in many pathological conditions. The role of the proteins involved remains largely unknown, and few vascular-specific drug targets have been discovered. Previously, in a screen for angiogenesis regulators, we identified Paladin (mouse: X99384, human: KIAA1274), a protein containing predicted S/T/Y phosphatase domains. We present a mouse knockout allele for Paladin with a β-galactosidase reporter, which in combination with Paladin antibodies demonstrate that Paladin is expressed in the vasculature. During mouse embryogenesis, Paladin is primarily expressed in capillary and venous endothelial cells. In adult mice Paladin is predominantly expressed in arterial pericytes and vascular smooth muscle cells. Paladin also displays vascular-restricted expression in human brain, astrocytomas, and glioblastomas. Paladin, a novel putative phosphatase, displays a dynamic expression pattern in the vasculature. During embryonic stages it is broadly expressed in endothelial cells, while in the adult it is selectively expressed in arterial smooth muscle cells.