Arsenic Trioxide (ATO) leads to an increase in ATRA induced expression in p47PHOX. Western analysis of total expression of p47PHOX is shown at 24h and 48h time points. p47PHOX is a key member of the NADPH oxidase complex which generates Reactive Oxygen Species (ROS). An upregulation in the expression of p47PHOX is seen at both 24h and 48h, with the difference being more apparent at 48h. Protein lysates were extracted from untreated cells, and cells treated with ATRA, ATRA-ATO combination, and ATO alone. Loading control is shown by GAPDH levels. This suggests that ATO directly affects the ROS part of differentiation machinery also, apart from increase in MAPK proteins.