CDK5 and glioblastoma: In order to determine whether the quinazolinone modulators of CDKCONF5 fluorescence indeed affected CDK5 activity, we performed CDK5 kinase inhibition assays with 10−5M of these compounds using the CDKACT5 activity biosensor developed in our group and U87 glioblastoma cell extracts as a source of CDK5 kinase (Peyressatre et al., 2020) (Figure 3A).