A study in mice demonstrated that the mir-449c was identified as an up-regulated known miRNA in thymus tissue following whole-body ionizing radiation exposure [Chen et al. DOI:10.1080/09553002.2016.1207821]. A review summarizing radiation biomarkers noted that the mir-449c is specifically expressed in spleen tissue and also in the kidney and small intestine, indicating its tissue-specific distribution [Jia et al. DOI:10.3389/fcell.2022.861451].