Moreover, Cyr61 was also a tumour-promoting protein in breast cancers (Liotta and Kohn, 2001; Xie et al, 2001a), which was similar to our findings in PCas; thus the loss of Cyr61 in PCa cells might also inhibit cell invasion by blocking the expression of matrix metalloproteinase-1. Here, CCN1 is linked to breast carcinoma.