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. 2012 Sep 11;3(9):1026–1035. doi: 10.18632/oncotarget.640

Figure 4. ATM-mediated phosphorylation of CK1δ promotes CK1δ localization, and subsequent phosphorylation of Mdm2 to trigger Mdm2 degradation.

Figure 4

(A) ATM-mediated phosphorylation of CK1δ promotes CK1δ nuclear localization. Immunofluorescence and DAPI staining of U2OS cells transfected with the indicated Myc-CKIδ constructs. Cells were treated with or without 10μM doxorubicin for 1 hour before fixation. (B) Stability of the Mdm2 protein is controlled by ATM. U2OS cells were infected with the indicated lentiviral shRNA construct and selected with 1 μg/ml puromycin to eliminate the non-infected cells. The resulting U2OS cell lines were transfected with the indicated HA-Mdm2, Flag-β-TRCP1 and Myc-CKIδ constructs. Immunoblots were performed to monitor the changes of HA-Mdm2. p1 and p2 are two of the three identified major PEST-sequence containing motifs that contain the identified CKI-phosphorylation sites.