Endogenous fragment of hemoglobin, neokyotorphin, as cell growth factor 1 1 Abbreviations: FBS - fetal bovine serum; FALS - forward angle light scattering; MTT - 3-(4;5-dimethylthiazol-2-yl)-2.5-diphenyl tetrazolium bromide; SRB - sulforhodamine B.