Kruppel Like Factor 9 (KLF9)

Krueppel-like factor 9 is a transcription factor that binds to GC box elements located in the promoter. Binding of the encoded protein to a single GC box inhibits mRNA expression while binding to tandemly repeated GC box elements activates transcription.Sequence analysis revealed that, like Sp1, Bteb contains 3 consecutive zinc finger motifs. In transient transfection experiments both Bteb and Sp1 stimulated promoters with repeated GC boxes.

Activation of naive B cells through CD40 and B-cell receptor downregulated expression of these cellular quiescence-associated transcription factors. Overexpression of KLF4, KLF9, and PZLF in memory B cells delayed their entry into cell division and proliferation.