- PSF acts through the human immunodeficiency virus type 1 mRNA instability elements to regulate virus expression. Zolotukhin, A.S., Michalowski, D., Bear, J., Smulevitch, S.V., Traish, A.M., Peng, R., Patton, J., Shatsky, I.N., Felber, B.K. Mol. Cell. Biol. (2003)