Phosphorylation puts the pRb tumor suppressor into shape.

In this issue of Genes & Development, Burke and colleagues (pp. 1156-1166) describe how the structure of retinoblastoma protein (pRb) is altered by phosphorylation at T373 or S608. These modifications cause specific conformational changes and alter pRb's interaction with E2F via two distinct mechanisms. The structures suggest that the panel of phosphorylation sites represents a versatile set of tools that are used to sculpt pRb in precise, but very different, ways.