On page 850 in the February 1, 2000, issue, there are errors in Figure 5. The authors have provided a replacement Figure 5, incorporating a new image for the Western blot for Cdk2 after immunoprecipitation of Cdk2. The original Figure 5 IP Cdk2/WB Cdk2 used in the Blood manuscript was inadvertently used in a figure representing a different experiment in another manuscript. During the investigation of this problem, a validated Cdk2-IP/WB gel was located and has now been used to replace the row in question. In addition, black lines have been added to the row showing the IP + WB for cyclin E and the row showing the kinase assay, per Blood's current policies, to indicate that blank lanes were spliced out. The authors removed the quantification under the lanes and revised the figure legend by deleting the last sentence, which read, “Relative protein levels/kinase activity values are shown below all lanes (PLL-nonadherent is arbitrarily 1).” The correct figure and legend are shown.