Oestrogen-induced uterine protein: presence of associated phosphoprotein phosphatase activity before oestrogen treatment

The phosphoprotein phosphatase (PPPase) activity that is found associated with oestrogen-induced protein(s) is not itself induced by oestrogen. Indeed, this activity was found at the same electrophoretic position (i.e. the position of the oestrogen-induced protein) and in equal amounts relative to the total PPPase activity, whether the cytosol fraction from control or from stimulated uteri was tested.