FN1 and varicocele: Some of the more abundant proteins in the unilateral varicocele group were lactotransferrin isoform 1 precursor (LTF), fibronectin isoform 3 preprotein (FN1), semenogelin-2 precursor (SEMG2), A-kinase anchor protein 4 isoform 2 (AKAP4), and semenogelin-1 preprotein (SEMG1).