Figure 6. PCNA repressed Prox1 transactivation of the chicken βB1-crystallin promoter in transfection assays. A: Prox1 activated the expression of reporter constructs consisting of either the 3XOL2 element cloned upstream of the β-actin minimal promoter or the full length chicken βB1-crystallin promoter (−432/+30). While PCNA did not have a measureable effect on either construct alone, cotransfection of the Prox1 and PCNA expression vectors resulted in a significant repression of Prox1 mediated activation. B: Increasing the amount of PCNA expression vector to 1 μg resulted in more robust transcriptional repression. P values were calculated using Student’s t-test.