RT-PCR analysis showing the reexpression of methylated tumor suppressor genes in unmutated CLL. Three different candidate tumor suppressor genes—(A) IGSF4, (B) ABI3, and (C) VHL—were investigated in 3 IGHV unmutated CLL samples (UM1 to UM3, shown in different colors) with and without treatment using the methyl inhibitor DAC, the HDAC inhibitor TSA, or in combination. Con indicates control.