ALTERATIONS OF THE PPP2R1B GENE IN HUMAN LUNG AND COLON-CANCER

The PPP2R1B gene, which encodes the beta isoform of the A subunit of t he serine/threonine protein phosphatase ZA (PP2A), was identified as a putative human tumor suppressor gene. Sequencing of the PPP2R1B gene, located on human chromosome 11q22-24, revealed somatic alterations in 15% (5 out of 33) of primary lung tumors, 6% (4 out of 70) of lung tu mor-derived cell lines, and 15% (2 out of 13) of primary colon tumors. One deletion mutation generated a truncated PP2A-A beta protein that was unable to bind to the catalytic subunit of the PP2A holoenzyme. Th e PP2R1B gene product may suppress tumor development through its role in cell cycle regulation and cellular growth control.