Such experiments define the molecular events and factors regulating the commitment of cells to the megakaryocytic lineage, and ultimately, the release of platelets into the bloodstream. In the absence of normal polyadenylation the more 5' gene uses the polyadenylation site within its 3' neighbor, the platelet GP Ib gene. This newly identified 5' gene contains an open reading frame encoding 369 amino acids with a high degree of sequence similarity to an expanding family of GTP-binding proteins, referred to as septins. However, a unifying functional property of septin proteins is their involvement in cytokinesis. GP Ib gene is also present within the homologous mouse locus with a remarkable conservation of gene sequence and structure.
Hematogenous metastasis requires tumor cell attachment to the vessel wall during blood flow.
In an in vitro perfusion system, tumor cell arrest involved tumor cell interaction with activated platelet via b3 integrins and crosslinking plasma proteins. Therefore, we analyzed critical flanking sequences surrounding the RGD site and the conformational contstraints of the RGD domain that are crucial in determining the ligand specificity for tumor cell integrin avb3 and platelet integrin aIIbb3. This information will be important for the development of inhibitors of tumor cell-platelet interaction. Another receptor of potential importance in tumor cell adhesion to vascular cells is ICAM-1. We found a clear correlation between ICAM-1 expression and tumor progression in melanoma patients indicating a role for this molecule in melanoma cell adhesion during the metastatic cascade.