KRT4 and atopic eczema: The aberrant differentiation and hyperproliferation of keratinocytes observed when cytoneme extension was inhibited in peridermal keratinocytes (krt4+) or Notch signaling was inhibited in undifferentiated keratinocytes (krtt1c19e+) are hallmark features of many human skin diseases such as psoriasis, atopic dermatitis, and more (Gratton et al., 2020; Armstrong and Read, 2020; Figures 3 and 4).