However, unexpectedly, the relative fold change in TGFβ-induced mRNA expression of major EMT-regulatory factors (ZEB1, ZEB2, TWIST, SNAIL and SLUG), whose expression is positively regulated in a Smad-dependent manner [12], was markedly lower in TD cells than in control cells, despite the higher basal expression levels of these genes (except for TWIST) in TD cells (Figure 2A). Here, SNAI1 is linked to thanatophoric dysplasia.