In animal cells, the endogenously produced $\text{miRNAs}$ silence gene expression by

1. base pairing with the $3’$-untranslated region of specific $\text{mRNAs}$
2. blocking $\text{mRNA}$ synthesis
3. binding to the operator site
4. base pairing with the $3’$ region of specific $\text{rRNAs}$