LARP1 (La ribonucleoprotein 1) is a key RNA-binding protein that regulates mRNA translation and stability, particularly for terminal oligopyrimidine (TOP) mRNAs encoding ribosomal proteins 1. LARP1 directly binds non-translating ribosomal subunits through a previously uncharacterized domain that occludes the mRNA channel of the 40S subunit, forming repressed LARP1-ribosome-TOP complexes 1. The protein functions as a critical regulator in the mTOR signaling pathway, where TOR-dependent LARP1 phosphorylation controls TOP mRNA translation to coordinate protein synthesis with cellular growth and proliferation 23. LARP1 protects mRNA 3' poly(A) tails from deadenylation through direct interactions with poly(A)-binding protein (PABP), contributing to mRNA stabilization 4. The protein is involved in multiple cellular processes including stress granule formation, mitochondrial function regulation, and response to cellular stress 56. LARP1 shows clinical significance as it is upregulated in malignant cells and impacts cancer immunotherapy responses through metabolic reprogramming pathways 27. However, controversy exists regarding whether LARP1 primarily activates or represses TOP mRNA translation under different conditions 8.