Final answer:
The sites of mRNA decapping and degradation are called P bodies, which are crucial for regulating mRNA turnover and gene expression after export from the nucleus.
Step-by-step explanation:
The sites of mRNA decapping and degradation are known as P bodies. Proteins in the nucleus participate in the export of the mRNA, facilitating its movement from the nucleus into the cytoplasm. Post-export, when the mRNA is in the cytoplasm, regulatory processes such as decapping and degradation can occur. These processes are essential for mRNA turnover and regulation of gene expression.