RBPJ and arteriovenous hemangioma/malformation: Notch1, as well as its essential transcriptional co-factor Rbpj-k [also known as CSL, Su(H), CBF] are essential regulators of arteriovenous (AV) patterning in the early vertebrate embryo, as their deletion leads to arteriovenous malformations (AVMs) and embryonic lethality (Krebs et al., 2004, 2000).