Wnts and BMPs are target genes of KGF. (A) Analysis of gene transcription by qRT-PCR in adult TECs. Six-week-old C57BL/6 mice were treated with KGF or HBSS as described in Figure 1 and sorted CD45⁻I-A^b+ TECs were analyzed on day 7 for mRNA expression of Wnt5b, Wnt10b, BMP2, and BMP4. Expression levels in KGF-treated mice (⊡) were compared with those in control mice treated with HBSS (x-fold change KGF vs HBSS, whereby the expression levels in the latter were set as 1.0; dotted line). (B) The increase in thymic cellularity in response to KGF depends on signals mediated by Smad4. Adult wild-type B6.129Smad4^lox/lox mice (− Cre) and [Smad4^lox/lox: Foxn1-cre]F₂ mice (+ Cre) were treated with KGF (⊡) or HBSS (▪). Six and 15 weeks after the initiation of treatment, total thymocyte cellularity was determined. Absolute thymocyte numbers (× 10⁻⁶) are shown. Mean ± SD versus HBSS controls. For data shown in panel A, 3 experiments were performed whereby material from 15 mice was pooled for each experiment.