XRCC6 and plasma cell myeloma: In addition to the verification in four independent experiments using two different MS/MS systems, the interaction of mdig with XRCC5 and XRCC6 was also confirmed in two other cell types, the human bronchial epithelial cell line BEAS-2B (Figure 6) and human multiple myeloma cell line H929 (Wu et al, unpublished observations).