GRB2 is recruited by phosphorylated SHC1 in the IL15 receptor complex (Zambricki et al. 2005, Gadina et al. 2000), as it is in the Interleukin-2 receptor complex (Li et al. 1994, Bennett et al. 1994).More in detail, human and mouse IL15 have 70.2% amino acid sequence similarity and exhibit similar trans-presentation mechanism, signal transduction machinery and biological activities. Similarly, human IL15 shows cross-reactivity with mouse cells and it was demonstrated that human and mouse IL15 showed similar responses in mouse models (Stoklasek et al. 2006) (Patidar et al. data not published).