- The mRNA of the translationally controlled tumor protein P23/TCTP is a highly structured RNA, which activates the dsRNA-dependent protein kinase PKR. Bommer, U.A., Borovjagin, A.V., Greagg, M.A., Jeffrey, I.W., Russell, P., Laing, K.G., Lee, M., Clemens, M.J. RNA (2002)