Nuclear poly(A) binding protein 1 (PABPN1) mRNA levels are low in skeletalmuscle. (A) Structure of the 2.1 kb and 1.4 kb PABPN1 transcripts (solidboxes represent coding regions and open boxes non-coding regions). (B)Total RNA from different mouse tissues was analyzed by northern blot using aPABPN1 probe. Two different exposures, short and long, are shown. 18S rRNA wasprobed as a loading control. Figure is representative of at least threeindependent sets of tissues.