Although both radiolabeled cetuximab and panitumumab demonstrated in vivo HER1- targeting characteristics, disparities were observed with blood clearance and non-target organ uptake. Cetuximab is a chimeric IgG1 mAb, whereas panitumumab is a fully human IgG2 mAb and binds to a different epitope of the HER1 antigen than cetuximab. Antibodies are usually cleared through their interaction with the Fc receptors expressed on cells of the reticuloendothelial system. The slower firstphase blood clearance of 86Y-CHX-A����-DTPA-panitumumab may be attributed to the fact that panitumumab is an IgG2 whereas cetuximab is an IgG1. IgG2 antibodies have lower affinity and binding to the Fc-gamma receptors than the IgG1 and therefore are cleared more slowly by this mechanism. For this reason, panitumumab presents as a better alternative than cetuximab for HER1-targeted imaging and RIT. The HER1- targeting characteristics of radiolabeled panitumumab shown here points to its potential as a great diagnostic tool for detection and NVP ADW 742 staging of MM. The results also point to the potential of panitumumab as a vehicle for delivering therapeutic radioactivity to HER1-expressing MM tumors. This approach to MM therapy should improve outcomes for HER1 over-expressing tumors that have not responded to classical HER1 therapy with TKIs and monoclonal antibodies due to resistance. Centaurins comprise a family of multidomain proteins that regulate a variety of cellular processes including cell survival, cell cycle progression, cell migration, receptor and endosome trafficking, gene transcription as well as development of dendrites and synapse conductivity. Misregulation of their expression and defects in function have been associated with Alzheimer��s disease and a number of cancers, such as glioblastomas, sarcomas or neuroblastomas domain mediating membrane recruitment and a GTPase-activating domain catalyzing hydrolysis of GTP on ADP-ribosylation factor proteins. Ankyrin repeats at the C-terminus potentially mediate protein-protein interactions. In addition, members of the Centaurin gamma subfamily harbor an intrinsic GTPase domain whose activity can be modulated by the GAP domain, enabling them to act as molecular switches. In mammals, the Centaurin gamma homolog is encoded by the PIKE/CENTG1 gene from which three protein isoforms, termed PIKE -A, L, and -S are produced through alternative splicing from a H-9 dihydrochloride single gene locus. PIKE-L is the longest isoform and contains a proline-rich domain at its N-terminus. PIKE-S lacks both the ArfGAP domain and the C-terminal ankyrin repeats.