PUM3 (Pumilio RNA binding family member 3) is an RNA and DNA binding protein that plays essential roles in cellular stress response and ribosomal biogenesis. PUM3 binds to double-stranded RNA or DNA without sequence specificity and localizes primarily to the nucleolus, where it participates in the processing of 7S to 5.8S rRNA 1. The protein contains a highly conserved Pumilio-homology domain consisting of multiple tandem repeats that facilitate RNA binding 2. Under genotoxic stress conditions, PUM3 redistributes from the nucleolus to the nucleoplasm and inhibits poly(ADP-ribosyl)ation activity of PARP1 while preventing PARP1 degradation by CASP3 1. Recent proteomic studies have identified PUM3 as an interacting partner of topoisomerase I (TOP1), with both proteins showing similar relocalization patterns following DNA damage 3. The protein's stability and cellular functions are regulated by phosphorylation, particularly at tyrosine 259, which is critical for cell proliferation and clonogenic capacity 1. PUM3 has been identified as one of 24 important genes associated with chromosome 9 deletion syndrome, suggesting developmental significance 4. Additionally, PUM3 has emerged as a hub gene in colorectal cancer networks, indicating potential roles in tumorigenesis 5.