Flow cytometry of Phospho-Rb (Ser807, Ser811) using U937 cells. Samples were incubated in monoclonal Phospho-Rb (Ser807, Ser811) antibody (Product # MA5-36944). Images correspond with the following conditions: untreated, unstained negative control (blue), untreated and stained (green), treated with lambda phosphatase and stained (red).