In A1 cells, E₂ induce ERK1/2 phosphorylation according to the proliferative/differentiation status.

<p>Western blot detection of p-ERK1/2 and ERK1/2 proteins in proliferating/undifferentiated (A) and non-prolifearting/differentiated A1 cells (C) treated at indicated time with 10 nM of E₂ and 10 mM of ICI 182–780. Two specific bands were observed respectively at 44 and 42 kDa. Each blot is representative of three separate experiments. The diagrams show the relative quantitation of p-ERK1/2 and ERK1/2 in proliferating (B) and non-proliferating (D) A1 cells. Data are expressed as ratios of p-ERK1-2/ERK1-2. In diagrams are also showed the different trend lines of the kinetic of p-ERK following E₂ stimulation. Asterisks represent p<0.01 when compared to control cultures treated with vehicle (ANOVA, Scheffè F-test).