RESUMEN
<p><b>OBJECTIVE</b>To investigate the differential expression of different types of Smads in keloids, normal scars and normal skins and its possible clinicopathological significance.</p><p><b>METHODS</b>RT-PCR and Western blot methods were used to examine the expression of Smads mRNA and proteins level in 10 cases of keloid, in 10 cases of normal scar and in 10 cases of normal skin tissues and fibroblasts. Fibroblasts of keloid, normal scar and normal skin were cultured in vitro. The expression difference were compared and analyzed by t-test, there was statistical difference when P < 0.05.</p><p><b>RESULTS</b>The mRNA and protein expression of inhibitory Smad7 were significantly down regulated in keloid compared with normal scar (P < 0.05) and normal skin (P < 0.05). However, no significant difference of the mRNA and protein expression of Smad2, 3 and the protein expression of phosphorylation of Smad2, 3 in keloid, normal scar, normal skin tissues and fibroblasts.</p><p><b>CONCLUSIONS</b>The decreased expression of Smad7 in keloid might play a significant role in the increased TGF-beta1/Smads signal transduction, which can not be terminated by autologous negative feedback cycle.</p>