Selective validation of microarray results by qRT-PCR and immunohistochemistry. Differential expression of transcripts identified by the microarray analyses was examined using (a) qRT-PCR and (b) immunohistochemistry. Additional colon tumors from five ApcMin/+ (M; nuclear β-catenin-positive) mice and four Smad3-/- (S; nuclear β-catenin-negative) mice were harvested, and qRT-PCR was performed on nine genes that exhibited representative strong or subtle patterns in the microarray analyses. All nine patterns detected in the microarray set were validated by the qRT-PCR results. Alox12, Arachidonate 12-lipoxygenase; Casp6, Caspase 6; Matn2, Matrilin 2; Ptplb, Protein tyrosine phosphatase-like B; Sox21, SRY (sex determining region Y)-box 21; Spock2, Sparc/osteonectin, CWCV, and Kazal-like domains proteoglycan (testican) 2; Tesc, Tescalcin; Tpm2, Tropomysin 2; Wif1, WNT inhibitory factor; Stmn1, stathmin 1; Ptp4a2, phosphatase 4a2. In (a), *p < 0.05 and **p < 0.01.