Figure 5. The stability of CyclinD1 and CDK4 in the nucleus limits the cell cycle progression of the tumour. (A) The amount of total CyclinD1 in the nucleus is not upregulated. (B) Effective reduction in CyclinD1 levels in the nucleus. (C, D) P21 can reduce the levels of phosphorylated CyclinD1 in the nucleus and stabilize its CyclinD1 binding to CDK4. (E) Co-IP confirmed that SOCS1 recruited ubiquitin and reduced the stability of CyclinD1/CDK4 complexes. (F) The high level of SOCS1 expression indicates low recurrence and better prognosis in patients with HCC.