Related Experiment Video
Updated: Jul 15, 2026

Through the Looking Glass: Time-lapse Microscopy and Longitudinal Tracking of Single Cells to Study Anti-cancer Therapeutics
Published on: May 14, 2016
p21(WAF1/Cip1) retards the growth of human squamous cell carcinomas in vivo
1Oral and Pharyngeal Cancer Branch, National Institute of Dental Research, Bethesda, MD 20892-4330, USA. cardinali@a1.cber.fda.gov
Abstract:
The excessive proliferation exhibited by cancer cells is frequently a result of their failure to adequately regulate cell cycle progression. In the present study, we developed a xenograft model of oral cancer in athymic mice, using squamous carcinoma cell lines and examined the ability of the cyclin-dependent kinase inhibitor p21 (WAF1/Cip1) to retard tumour growth in vivo, using a retroviral delivery system. Human p21 cDNA was cloned by polymerase chain reaction, expressed, and the encoded protein shown to have biological activity in in vitro kinase assays. Amphotropic retrovirus cultures which expressed recombinant p21 were generated and used to treat established squamous cell carcinoma xenografts. Two weeks following onset of treatment tumours injected with p21 virus producer cells showed a reduction in size between 3- and 10-fold compared with tumours which received control cells which produced control virus alone. The data indicate that recombinant p21 may be of future use for therapeutic intervention in oral cancer.
Related Concept Videos
Negative Regulator Molecules
Inhibition of Cdk Activity
Replicative Cell Senescence
Abnormal Proliferation
Loss of Tumor Suppressor Gene Functions
When the tumor suppressor genes develop mutations or are lost, cells start growing out of control, leading to cancer. However, a single functional copy of the tumor suppressor gene is enough for the cells to maintain their normal functions and cell...
The Retinoblastoma Gene
The first-ever tumor suppressor gene called Rb was identified in retinoblastoma - a rare eye tumor in children. In inherited forms of the disease, a child inherits one defective copy of the Rb gene, which predisposes them to retinoblastoma. However,...

