We observed nearly a five-fold increase in bone metastasis occurring from the primary TM40D-COX2 tumor (50%) compared to the bone metastasis occurring from the TM40D (control vector) tumor (11%) or TM40D-MB-shCOX2 (0%), validating the metastasis-promoting action of COX2 in our mammary tumors (Figure 1B, p<0.05). This evidence concerns the gene PTGS2 and breast cancer.