Protein expression using a polyclonal antibody (ERβ) raised against the ERβ amino terminal. 25 μg of protein was loaded. [A] Representative Western blot for ERβ and actin (which was used as an internal standard for normalizing the data); the calculated size of the band is indicated on the left-hand side of the gel. Four bands of apparent molecular weight of 76, 59, 54 and 41 kDa were detected for ERβ. [B] Ontogenic profile: ERβ protein was expressed relative to actin. Results shown are mean ± S.E.M. from four different dams; a significant decrease in ERβ protein expression (p < 0.001) was detected between 16 and 19 dg and 16 and 21 dg for both the 59 and the 54 kDa ERβ bands (LSD test).