Kruppel-like factor (KLF) 9, KLF13, KLF14, KLF16, and similar proteinsKruppel/Krueppel-like transcription factors (KLFs) belong to a family of proteins, called the Specificity Protein (SP)/KLF family, characterized by a C-terminal DNA-binding domain of 81 amino acids consisting of three Kruppel-like C2H2 zinc fingers. These factors bind to a loose consensus motif, namely NNRCRCCYY (where N is any nucleotide; R is A/G, and Y is C/T), such as the recurring motifs in GC and GT boxes (5'-GGGGCGGGG-3' and 5-GGTGTGGGG-3') that are present in promoters and more distal regulatory elements of mammalian genes. Members of the KLF family can act as activators or repressors of transcription depending on cell and promoter context. KLFs regulate various cellular functions, such as proliferation, differentiation, and apoptosis, as well as the development and homeostasis of several types of tissue. KLF9, KLF10, KLF11, KLF13, KLF14, and KLF16 share a conserved alpha-helical motif AA/VXXL that mediates their binding to Sin3A and their activities as transcriptional repressors. In addition to the C-terminal DNA-binding domain, each KLF also has a unique N-terminal activation/repression domain that confers specificity and allows it to bind specifically to a certain partner, leading to distinct activities in vivo. This model represents the related N-terminal domains of KLF9, KLF13, KLF14, KLF16, and similar proteins.