P.S. to PS (phosphatidylserine)--pertinent proteins in apoptotic cell clearance.

The psr protein has been proposed as the critical receptor that detects phosphatidylserine (PS) on the surface of apoptotic cells. However, for some time there has been evidence that this protein is not at the cell surface but in the nucleus. Now, the phenotype of a knockout of the Drosophila psr protein (dPSR) has discredited the identification altogether, lending impetus both to uncovering the real function of the protein and to identifying the real PS receptor. Interpretations of studies of two other genes supposedly involved in PS transport may be built on similarly shaky foundations.