MCF-7 cell progesterone receptor (PGR) is additionally modulated by sex steroid binding protein (SBP) and its membrane receptor (SBP-R) through cAMP and PKA. - Fortunati,N.; Comba,A.; Becchis,M.; Catalano,M.G.; Fazzari,A.; Fissore,F.; Frairia,R. (Ann N Y Acad Sci, 1996)