BTD and neoplasm: Several of the proteins whose level changes early for some tumor types (glyceraldehyde-3-phosphate dehydrogenase (GAPDH), B4GalT1, death receptor 6 (DR6, also known as tumor necrosis factor receptor superfamily member 21 (TNFRSF21), sulfhydryl oxidase 1 (QSCN6), arginosuccinate lyase (ASL), DLD, tryptophanyl-tRNA synthetase (WRS), biotinidase (BTD) and NDPK are among the 15 shared biomarkers that indicate the presence of any of the four tumor types studied.