Describe how RBPs can prevent miRNAs from degrading an RNA molecule.
RNA binding proteins (RBP) bind to the RNA and can either increase or decrease the stability of the RNA. If they increase the stability of the RNA molecule, the RNA will remain intact in the cell for a longer period of time than normal. Since both RBPs and miRNAs bind to the RNA molecule, RBP can potentially bind first to the RNA and prevent the binding of the miRNA that will degrade it.
How can external stimuli alter post-transcriptional control of gene expression?
External stimuli can modify RNA-binding proteins (i.e., through phosphorylation of proteins) to alter their activity.