Intact or protein extracts from COS-7 cells transiently transfected with expression vectors for wild type (WT) and mutant (F1–3) DsRed-hNT5E fusion proteins were assayed for AMPase activity as described in “Materials and Methods” section. A. Surface AMPase activity is only found in transfected cells transiently expressing DsRed-hNT5E wild type fusion protein (DsRed-hNT5E WT vs. MOCK; p value<0.0001, n = 3). No AMPase activity was detected in mock-transfected cells as expected, or transfected cells transiently expressing DsRed-hNT5E F1-3 proteins (DsRed-hNT5E F1, -F2, -F3 vs. MOCK; p value<0.0001, not significant, ns, n = 3). B. AMPase activity is only measured in protein extracts from transfected cells transiently expressing DsRed-hNT5E wild type fusion protein (DsRed-hNT5E WT vs. MOCK; p value<0.0001, significant, ***, n = 3). Mock-transfected cells or transfected cells transiently expressing DsRed-hNT5E F1–3 proteins lack any measurable AMPase activity (DsRed-hNT5E F1, -F2, -F3 vs. MOCK; p value<0.0001, not significant, ns, n = 3).