Suppose a mutant RNA polymerase II is used that lacks one of the phosphorylation sites on the C-terminal tail. The mRNA synthesized using the mutant RNA polymerase lacks a poly-A tail. Inside cells, no protein is synthesized from this mRNA. How could this be explained? Choose one or more:
A. The mRNA is not transported out of the nucleus.
B. Some exons are mistakenly removed from the RNA.
C. The mRNA is rapidly degraded.
D. The ribosome cannot find the translation start codon.
