Oct-1 is shown to be an oncoprotein because of its known role as an activator of the histone H2B gene and the importance of this gene during DNA synthesis. To determine the role of Oct-1 as an oncoprotein, the cell line 5637 (ATCC HTB9) was transfected with the vector pcDNA3 containing full length, antisense Oct-1 cDNA. This cell line is Rb-defective and has been shown to have increased Oct-1 binding activity as compared to Rb reconstituted clones. After transfection, Oct-1 antisense clones were grown and assayed for the loss of oncogenic characteristics as compared to control transformants.