PTN and neoplasm: Examples of down-regulated genes include EEF1A2 (< 60 fold) which is highly expressed in many tumor types [19], XAGE1A, a well-known tumor/testis antigen gene (down-regulated < 30 fold) [20] and pleiotrophin (PTN), which is highly expressed in small cell and NSCLC, was down-regulated 16 fold in cells from lung tumor specimens cultured under CRC conditions [21].