NFKBIZ and melanoma: While NFKBIZ mRNA was detectable in varying levels in all investigated melanoma cell lines, a subfraction of cell lines (including human melanoma cell lines LOX-IMVI, SK-MEL-30, and SK-MEL-5, or murine melanoma cell lines D4M-3A and YUMM1.7) displayed constitutive IκBζ protein expression (Fig. 1a).