Figure 1. Transcription factor 21 (TCF21) participates in development and tumorigenesis through distinct mechanisms. A, In development, TARID recruits components of the BER demethylation pathway and activates TCF21 expression by inducing promoter demethylation. Expression of TCF21 contributes to mesenchymal-epithelial transition (MET) and embryogenic development/differentiation of organs through different factors. B, In tumorigenesis, TCF21 is hypermethylated, and silencing by microRNAs (miRNAs) may contribute to epithelial-mesenchymal transition (EMT) and tumor progression. TARID: TCF21 antisense RNA inducing promoter demethylation; BER: TDG dependent base excision repair; GADD45A: growth arrest and DNA damage inducible alpha; TET: ten eleven-translocation family of dioxygenases; TDG: thymine DNA glycosylase and trimethylation of histone H3 at lysine 4 (H3k4me3).