The pSos vector are designed for constructing and expressing gene fusions with the hSos protein and a myristylation signal, respectively. The pSos vector contains DNA encoding amino acids (aa) 1 to 1067 of the hSos gene and unique 3? cloning sites.2 It is used for constructing a bait plasmid containing a DNA insert encoding a bait protein. The ADH1 promoter driving expression of the hSos-bait fusion is constitutively active