NFKBIA and intrahepatic cholangiocarcinoma: In intrahepatic cholangiocarcinoma (ICC) models, the translation product of circPCSK6, circPCSK6-167aa, competitively binds to the RING domain of the E3 ubiquitin ligase RBBP6, inhibiting K48 ubiquitination of IKBα and preventing its degradation.