CD274 and breast carcinoma: Similarly, in cervical and breast cancer cells, cyclin D1-CDK4 kinase was reported to destabilize PD-L1 and increase TILs via phosphorylating cullin 3-speckle type POZ protein (CUL3SPOP) E3 ligase, leading to the ubiquitination of PD-L1 (345, 346).