Fig. 6. Eda-A1 upregulates transcription of Shh, but recombinant Shh is unable to rescue hair placode induction in Eda-deficient skin. (A) Eda-deficient skin explants were cultured in the absence or presence of Eda-A1, as depicted in Fig. 4A, and Shh expression was analysed by quantitative RT-PCR. A 2.5-fold induction of Shh was evident already after 1 hour of treatment, and was highest after 3-4 hours of treatment. (B) The number of Shh transcripts was increased in E14 K14-Eda-A1 skin compared with control littermates. (C-F) Eda-deficient E13 skin explants cultured for 1 day in the control medium are devoid of hair follicles and no rescue is detected with 0.1 µg/ml, 0.5 µg/ml or 1.0 µg/ml recombinant Shh.