Probable transcription factor that regulates carpel integuments formation. Required for the specification of polarity in the ovule inner integument. Modulates the content of flavonols and proanthocyanidin in seeds. Expressed in the periphery of the primary root apex and lateral root. During ovule development, first expressed in the inner integument primordium and then on the abaxial side of the inner integument. Ovules with a single integument instead of two. Plants overexpressing KAN4 show reduced or absent ovule outer integument and color alteration of the seed coat.