Silencing CycG2 expression blunts fulvestrant-induced dephosphorylation of Rb, inhibition of MEK/ERK signaling, and downregulation of Raf1. Immunoblot analysis of the indicated cell cycle regulatory and MAP kinase pathway proteins in MCF7 control (WT, NSC) and CycG2 KD (1-B, ID3) clones cultured with (+) or without (-) fulvestrant (ICI, 100 nM) for 48 h (A, C, E-H) or (B,D) E2-depletion (DM). Immunoblots for (A, B) S780 pRb and total Rb, (C, D) CycD1, E) T202/204 pERK 1/2, total ERK, (F) S217/221 pMEK1/2 and total MEK, (G) total cRaf, and (G) S338 p-cRaf are shown atop the indicated loading controls (GAPDH, α-tubulin, or β-actin). Numbers below lanes in blot panels indicate relative expression levels normalized to level in non-treated no-knockdown control (MCF7 WT or NSC control set at 1, marked with an *). Band intensity quantification is relative to amount of either loading control (GAPDH (GDH), α-tubulin (Tub) or β-actin (β−Act)) or total Rb, ERK, or MEK as indicated.