Rb9 is a flexible, hairpin forming, cyclic peptide, with an exposed disulfide bridge.
Rb9 but not the analogous linear Rb10, forms an α–helix stabilized by H-bonds.
Tumor cells hyperadherence and migration inhibition are cysteine-linked Rb9 effects.
Rb9 attenuates Hsp90 chaperone functions and activates adherence GPCR signaling.
Rb9 is a strong evidence of the bioactivity of isolated immunoglobulin CDR peptides.