We have previously shown that specific RNA binding proteins (RBP) are activated by genotoxic stress. The role and function of these stress-activated RBP are, however, poorly understood. The data presented here indicate that the RBP A18 hnRNP is induced and translocated from the nuclei to the cytoplasm following exposure to UV radiation. Using a new in vitro system we identified potential cellular targets for A18 hnRNP. Forty six mRNAs transcripts were identified, most of which are stress or UV responsive genes. Two important stress-responsive transcripts, the replication protein A (RPA2) and thioredoxin, were studied in more detail. Northwestern analyses indicate that A18 hnRNP binds specifically to the 3'Untranslated region (UTR) of RPA2 transcript independently of its polyA tail while the polyA tail of thioredoxin mRNA reinforces binding. Overexpression of A18 hnRNP increases the mRNAs stability and consequently enhances translation in a dose dependent manner. Moreover, cell lines expressing reduced levels of A18 hnRNP are more sensitive to UV radiation. These data suggest that A18 hnRNP plays a protective role against genotoxic stresses by translocating to the cytosol and stabilizing specific transcripts involved in cell survival.