KLF4 and neoplasm: Conversely, Smad4, a well‐known tumour silencer and a major regulator of intracellular TGF‐β1 signalling, was up‐regulated after knockdown of KLF4 expression (Figure 1A,B).22 Knockdown of KLF4 expression also strongly reduced the number of CSCs as assessed by a LDA (Figure 1C).