N4BP1 and neoplasm: The interaction with the HECT ligase Itch, on the contrary, does not seem to be followed by N4BP1 ubiquitination, but rather N4BP1 counteracts the activity of the Itch E3-ligase by directly competing with Itch substrates, such as c-Jun and the members of the p53 family, p63 and p73, thus suggesting a role as promoter of tumor progression [7].