“…In our studies, the steady-state levels of 18S rRNA remained constant in response to various hormonal manipulations. Also, this is in keeping with recent reports recommending the use of rRNA gene expression as a preferred RNA-loading (internal) control for Northern blot analysis in which total RNA is used (Barbu & Dauty, 1989;Perrella et al, 1994;Yang & Tashjian, 1993;DeLeeuw et al, 1989;Bhatia et al, 1994). More widely used internal controls such as glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and β-actin were not employed in the current studies, since the steady-state levels of these mRNAs are known to be greatly influenced by hormones and growth factors (Alexander et al, 1988;Wadsworth et al, 1990;Bray et al, 1991;Sabath et al, 1990;Skinner et al, 1985;Amsterdam & Rotmensch, 1987;Amsterdam et al, 1989;Reaven et al, 1994).…”