Hill-Slope plots of the increased invasion-inhibitory potency of Ac-PHSCNGGK-MAP as compared with the Ac-PHSCN-NH2 peptide with naturally serum-free, selectively permeable basement membranes from sea urchin embryos as invasion substrates. Panel (a). Inhibition of serum–induced DU 145 invasion. Panel (b). Inhibition of serum–induced PC-3 invasion. Panel (c). Inhibition of Ac-PHSRN-NH2–induced, SF DU 145 invasion. Panel (d). Inhibition of Ac-PHSRN-NH2–induced, SF PC-3 invasion. X axes, log peptide concentration in nM; Y axes, mean percentages of invaded cells, relative to uninhibited, FBS– or PHSRN–stimulated controls (+/− SD). Black circles, Ac-PHSCNGGK-MAP; black triangles, Ac-PHSCN-NH2 peptide; black diamonds, Ac-HSPNCGGK-MAP; white circles, Ac-HSPNC-NH2 peptide; white squares, Ac-PHSCNGGK-Ova.