ARAP1 and lung adenocarcinoma: However, our results also indicate that there are other genes over expressed in our SAGE IPF libraries when compared to normal lung with an unknown role in IPF pathogenesis like syndecan 1(SDC1), suppression of tumorigenicity 5 (ST5, regulator of MAPK1/ERK2 kinase) and centaurin delta 2 (CENTD2); all of which have been associated with lung adenocarcinomas.