DKK1 and neoplasm: Interestingly, there was a substantial, statistically significant decrease in tumor growth velocity in the BHQ880-treated mice (0.47% volume increase every 3 days, compared with 0.95% in control mice, p < 0.0001; Figure 1B), but only during the early phase of tumor growth, when control mice had elevated serum DKK-1 levels.