Complex sentence: Hsp20 phosphorylation correlates well with smooth muscle relaxation and is one significant phosphoprotein envolved in the process, and also appears significant in development of the smooth muscle phenotype during development.
Split into simpler sentences: Hsp20 phosphorylation correlates well with smooth muscle relaxation and is one significant phosphoprotein envolved in the process. Hsp 20 appears significant in development of the smooth muscle phenotype during development.