Effects of rhEpo on invasion. RhEpo functions as a chemoattractant for HNSCC cell lines under study, promoting in vitro invasion. a Exposure of cells to rhEpo at 1 U/ml for 40 h increased invasion by 80% in UMSCC10B and 160% in UMSCC-22B compared to their respective controls. b Images of representative fields showing an increase in the number of Matrigel invading cells upon administration of rhEpo, although less significant than serum stimulation. Magnification = 100 ×.