TCF3 and embryonal carcinoma: Q-PCR analyses confirmed significant down-regulation of several WNT downstream genes and WNT targets including Brachyury, a WNT3 downstream target gene [44]; Ifitm1, a WNT/β-catenin-dependent downstream gene [45], [46], and Nkx1-2, which responds to WNT/β-catenin signalling and activates Brachyury expression through the suppression of Tcf3 (in P19 mouse embryonal carcinoma cells; [47]) in the E7.5 Dullard−/− embryo (Fig. S4).