ERBB4 and colorectal carcinoma: Although ErbB4 protein expression is solely detectable in more aggressive CRC cell lines35, 36, high levels of ErbB4 were found in about 43% of primary CRC tissue microarrays35, and the nuclear staining of its 80kDa cleaved fragment, able to participate in transcriptional events, correlated with poor prognosis35, 36.