Protein tyrosine phosphatases?

Question

They seem (from abstracts... I can't afford the subscriptions required for reading whole papers) to have a lot to do with differentiation, adhesion, migration and several other aspects of cancer cell development...

... but can anybody tell a layman (I'm a very bright and literate one but I'm pretty ignorant here) what they are and maybe a bit about how they do what they do?

Answer 1

For the most part, you can figure out what an enzyme does from the name if you know what to look for.  A phposphatase is an enzyme that removes a phosphate group from its substrate.  This one is a tyrosine phosphatase, meaning it removes the phosphate group from tyrosine residues on its substrate.  The MAP kinase family is one example of something that is regulated by phosphatases (and kinases, which add phosphate groups to things).  They're also involved in many other signaling pathways and many cellular processes.

Answer 2

any phosphatase will remove phosphate groups from a given amino acid (tyrosine in this case) in a protein.  Removal or addition of a phosphate can simply put activate or deactivate proteins.  In the case of cancer, you end up with proteins that are active that shouldn't be and they signal in many different pathways that tell the cell to survive, grow, change, move, replicate, etc.