passages.id: split_5_test_835_passage
passages.type: progene_text
passages.text: While co - transfection of HeLa cells with a B-Myb expression plasmid activated the transfected SP-A promoter about 3 - fold , co - transfection of B-myb with cyclin A and cdk-2 , to enhance phosphorylation of B-Myb , increased transcriptional activity of SP-A constructs approximately 20 - fold .