Detection of endogenous fer: Whole cell extracts of pervanadate (VH) treated tumor cells (20.000 cells per lane) were applied to SDS-PAGE and transferred to PVDF membranes. Immunoblots were probed with mab fer-6B9 (0.5 ug/ ml) for 1h at RT and developed by ECL (exp. time: 30 sec). VH treatment: 15 min. Lane 1: A431; Lane 2: SW480 lane 3: SW620; lane 4: HT29; lane 5: MCF-7; lane 6: MDA-MB231; lane 7: T47D