CTD Small Phosphatase Like Protein (CTDSPL)

CTDSPL gene was homozygously deleted in about 15% of major epithelial cancers. Expression of the CTDSPL gene was reduced more than 20-fold in 11 of 12 carcinoma cell lines and in 3 of 8 tumor biopsies. CTDSPL suppressed the growth of a small cell lung carcinoma cell line and a renal cell carcinoma cell line in culture, and it suppressed tumor formation in SCID mice. Following transfection in mammary carcinoma cells, both CTDSPL isoforms reduced the level of phosphorylated retinoblastoma protein , confirming that they function as phosphatases.

The longer deduced protein contains 276 amino acids, while the shorter protein lacks residues 79 to 89. Both proteins were expressed in the cytoplasm of transiently transfected cells.