Specific absence of Smad7 mRNA in particular hematopoietic cells.

(A) Northern blot analysis of mouse Smad7 mRNA. Each lane contained 2 μg of poly(A)⁺ RNA from the indicated mouse organs. A Smad7 probe (625-base pair [bp] complementary DNA [cDNA] fragment) revealed one major transcript in various tissues. Positions of RNA size markers (kilobase [kb]) are shown on the left. (B) RT-PCR analysis of Smad7 mRNA in different types of cells. The examined cell lines were mink Mv1Lu (lung epithelial), mouse Swiss-3T3 (embryonic fibroblast), F5-5 (erythroid leukemia), M1 (myeloblast), WEHI-3 (myelomonocyte), C7 (macrophage), P815 (mastocytoma), CTLL-2 (T lymphocyte), Sp2 (plasmacytoma), human HEL (erythroleukemia), K562 (chronic myelogenous leukemia), HL-60 (promyelocytic leukemia), and MEG-01 (megakaryoblast). cDNAs to 1 μg of RNA isolated from these cells were synthesized by reverse transcription with random primers. Equal aliquots from each reaction were subjected to PCR to amplify a Smad7 and a control G3PDH cDNA fragment. The PCR primer pairs and conditions were designed for amplification of a 207-bp Smad7 sequence in both rodent and human cells. The data indicate that F5-5, HEL, and K562 cells specifically lack Smad7 expression.