p27Kip, Kinase Inhibitory Protein 1 by IHC
Test Code
I p27KIP
Associations
kinase inhibitory protein 1
Methodology
Immunohistochemsitry; clone 1B4
CPT Codes
88342
Turnaround Time
3 days
Specimen Requirements
- Surgical samples received in 10% neutral buffered formalin
- Formalin fixed paraffin embedded tissue
- Previously prepared pathology materials (slides,smears, blocks or other samples)
Specimen Stability
Indefinitely at room temperature
Storage & Handling
Ship ambient. In extreme hot weather, ship with a cool pack.
Causes for Rejection
Inadequate fixation; Improper labeling
Description
p27 protein is a polypeptide which binds to cyclin E/cdk2 complexes (but not to cdk2 alone) and is detected in purified extracts of growth arrested cells.
p27 protein constrains cell proliferation by setting the threshold level of cyclin E necessary to activate cdk2. The 27kD protein is also present in proliferating cells but only in a sequestered form when it is unavailable to interact with cyclin E/cdk2 complexes. It is likely that cyclin D complexed with catalytically inactive cdk4 is sufficient to sequester p27 and titrate its function.
The presence of bound p27 in proliferating cells suggests that its role may not be restricted to inducing cell cycle arrest but to also set the cyclin E threshold for execution of the G1 to S phase transition during each mitotic cycle.
p27 protein constrains cell proliferation by setting the threshold level of cyclin E necessary to activate cdk2. The 27kD protein is also present in proliferating cells but only in a sequestered form when it is unavailable to interact with cyclin E/cdk2 complexes. It is likely that cyclin D complexed with catalytically inactive cdk4 is sufficient to sequester p27 and titrate its function.
The presence of bound p27 in proliferating cells suggests that its role may not be restricted to inducing cell cycle arrest but to also set the cyclin E threshold for execution of the G1 to S phase transition during each mitotic cycle.
References
- Wong S C C, Chan J K C, Lee K C, et al.(2001). Differential expression of p16/p21/p27 and cyclin D1/D3, and their relationships to cell proliferation, apoptosis, and tumour progression in invasive ductal carcinoma of the breast Journal of Pathology.194: 35–42
- Fernández-Figueras M T, Puig L, Penín R M, et al.(2000). Decreased immunoreactivity for cell-cycle regulator p27(Kip1) in Kaposi's sarcoma correlates with higher stage and extracutaneous involvement. Journal of Pathology. 191: 387–393
