TPO and neoplasm: Therefore, to assess the role of EphB4/EphrinB2 signaling on aRMS tumor progression, we competitively inhibited EphB4 forward signaling using a soluble EphB4 linked either to mouse or human serum albumin (sEphB4-MSA, sEphB4-HSA) [16] in both orthotopic allograft and xenograft models using 5 to 6-week old NOD scid gamma (NSG) mice.