To provide evidence that extracellular SerpinB2 can indeed result in shortening of cellular protrusions, small quantities of recombinant SerpinB2 and SerpinB2R380A (generated using transfected HEK239T cells) were incubated with SerpinB2−/− RPM and B16 melanoma seeded onto Matrigel. The gene discussed is SERPINB2; the disease is melanoma.