Kruppel-like Factor 2 [KLF2, also called lung Kruppel-like factor (LKLF)] is a transcription factor shown to be necessary for the maintenance of naive T cells. KLF2 is expressed in both naive and memory cells, and is proposed to promote quiescence in these populations. During T cell stimulation, both KLF2 protein and mRNA are down-regulated, and loss of KLF2 appears to be critical for full T ce...