IL-4 and TGF-β1 expression in the kidneys of (a) eight week-old and (b) seven day-old tg and wt mice. RNA samples from wt (a and b: lanes 2,3 and 7,8) and tg (a and b: lanes 4,5,6 and 9,10,11) kidneys, equalized with γGCS, were subjected to RT-PCR for IL-4 (a and b: lanes 2–6) and TGF-β1 (a and b: lanes 7–11). Only tg kidneys show IL-4 expression, as demonstrated by the 216 bp-band (a and b: lanes 4,5,6). Wt kidneys do not express IL-4 mRNA (a and b: lanes 2,3). Renal TGF-β1 expression is upregulated in eight week-old tg mice, as shown by the 360 bp-band (a: lanes 9,10,11); the TGF-β1 expression in adult wt kidneys is negligible (a: lanes 7,8). In contrast, the renal TGF-β1 expression in seven day-old wt mice (b: lanes 7,8) is stronger compared with tg littermates, which show only weak 360 bp-bands (b: lanes 9,10,11) indicating decreased TGF-β1 mRNA (ethidium bromide-stained agarose gels).