Researchers unravel important role of Rb tumor suppressor in aggressive form of breas
 

The retinoblastoma (Rb) protein plays a critical role in suppressing the multi-step process of cell migration through the bloodstream, lymphovascular invasion and the metastasis of an aggressive type of breast cancer to the lung, researchers at the University of Cincinnati (UC) Cancer Institute, the Cincinnati Cancer Center (CCC) and the UC Brain Tumor Center have found.

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Re: Researchers unravel important role of Rb tumor suppressor in aggressive form of b
 

This is how the Cyclin4,6 kinase inhibitors seem to work.
These Kinases phosphorylate the Retinoblastoma protein.
When the Retinomablastoma protein that acts as a cell growth inhibitor is phosphorylated, its action is inhibited. Drugs like Palbociclib and LEE011that inhibit the 4,6 cyclin kinase action keep the Retinoblastoma protein active as a cell growth supressor.

This growth inhibiting protein is not found in all cancers. As far as breast cancer is concerned, it is found in Estrogen Positive cancers more than estrogen negative breast cancer. This is why in clinical studies Palbociclib is combined with an aromatase inhibitor.

Paul