CDK4 and glioblastoma: These observations are consistent with a recent report showing that CDK2 or CDK4/6 expression strengthens Rb-Pin1 interaction in glioblastoma multiforme cell lines.39 Of note, the authors also reported that the Rb small pocket, which excludes the RbC, interacts with Pin1, as shown by GST pull-down assays in 293FT cells.39 The reasons for these discrepancies are unknown.