P21Edit

Before I write, could you clarify what you mean by "P21"? The term can refer to several different things, and I want to make sure I build the article on the correct topic. A couple of common possibilities:

• P21 as a biological term: the protein p21^Cip1/Waf1, encoded by the gene CDKN1A, which functions as a regulator of the cell cycle and has roles in cancer biology, aging, and stem cell biology.
• P21 as a political or organizational designation: a party, movement, or coalition that uses the shorthand P21 in a given country.

If you specify which P21 you have in mind, I’ll draft a well-structured encyclopedia article. I can aim for a neutral, balanced tone and include appropriate internal links like CDKN1A and cell cycle for the biology topic, or political party and country-specific terms for a political topic, using the term or term human readable here format as requested. If you’d like me to proceed with a neutral, cross-cutting overview that covers major perspectives, I can do that as well.

Would you like me to proceed with the biological P21 (the cell-cycle regulator) or a political/organizational P21?