Figure 6.

Influence of Sec61 mRNA knockdown on cyclin D1 expression. MDA-MB-468 cells or HeLa cells were transiently transfected with Sec61β siRNA and 72 h later EGF was added for the indicated times. (A) The cells were lysed and the expression of cyclin D and Sec61β was estimated by blotting, whereas nuclear extracts were blotted for c-Fos. Erk-1 or phospholipase C-γ1 were used as loading controls, as indicated. (B) Total RNA was isolated from control and EGF-treated and Northern blotted with a cyclin D1 probe. Cyclophilin3 served as a loading control. Also, control blots for Sec61β or Erk-1 are shown for both cell types. Control blots show equivalent level of EGFR in both cells types with or without siRNA knockdown by Sec61β (data not shown).