| Here we show that HIPK 2 phosphorylates the activation domain of Pax 6 , which augments Pax 6 transactivation by enhancing its interaction with p 300 . ^^^ Furthermore , the knock down of either endogenous or exogenous HIPK 2 expression with HIPK 2 shRNA markedly inhibited Pax 6 phosphorylation and its transactivating function on proglucagon promoter in cultured cells . ^^^ These results strongly indicate that HIPK 2 is an upstream protein kinase for Pax 6 and suggest that it modulates Pax 6 mediated transcriptional regulation . . ^^^ Phosphorylation and transactivation of Pax 6 by homeodomain interacting protein kinase 2 . ^^^ |