Krüppel is a gap gene originally described in Drosophila melanogaster, which encodes a zinc finger transcription factor with four tandemly repeated zinc finger domains.
Krüppel means, literally, "cripple" in German, named for the crippled appearance of mutant larva. Krüppel regulates the expression of several other gap genes.
See also Kruppel-like factors which have been recently investigated in the heart but are well characterized for their role in carcinogenesis.
References
Krüppel Wikipedia(Text) CC BY-SA