FIG. 6.

Proteins which mediate internal ribosome entry of c-myc are downstream of MKK6. HeLa cells were cotransfected with the dicistronic c-myc IRES-containing plasmid pGL3Rutr and either pcDNA3 (control empty vector), pcDNA3 containing DNA encoding MKK6WT, or pcDNA3 containing the constitutively active version of this kinase, MKK6Glu. Cells were harvested and assayed for luciferase activity to determine whether coexpression of the dicistronic plasmid with MKK6 increased cap-dependent (Renilla luciferase [RL] expression) and/or cap-independent (firefly luciferase [FL] expression) translation initiation. All experiments were performed in triplicate on three independent occasions.