Figure 3.

Expression analysis of the mutant SMN A2G transgene in transgenic mice. (A) RT-PCR on RNA from indicated tissues of an SMN A2G;Smn ^{+ / +} animal was performed as described in the Materials and methods. The β-actin gene was simultaneously amplified as a control. (B) Western blot analysis on 5-d-old type I SMA, type III SMA, and an Smn ^{+ / −} mouse was performed using the anti-SMN monoclonal antibody, MANSMA2. The blot was subsequently stripped and probed with an anti–β-actin antibody to control for loading amounts. Type I SMA mice produce very little SMN, which is visible only after longer exposures. (C) Western blot analysis on 3.5-mo-old type III SMA mice (heterozygous for the A2G transgene, Het.), type III SMA mice (homozygous for the A2G transgene, Hom.), and normal mice (Smn ^{+ / −}) using the anti-SMN monoclonal antibody, MANSMA2. β-actin or β-tubulin serve as loading controls.