Among animals in which tumors become established, kappa light chain levels are significantly higher in those animals bearing tumors that express soluble syndecan-1 ectodomain.

Numbers represent the total number of animals having detectable levels of kappa light chain in their serum. Animals not having detectable levels of kappa light chain are excluded from this analysis. Data for sSyn-1 is from 2 distinct soluble syndecan-1–expressing clones (sSyn-1.2 and sSyn-1.10) that behaved similarly in vivo. Values represent mean ± SE. (Median values were similar to means: neo = 86, Syn-1 = 83, sSyn-1 = 243.) *P < .0001 for neo versus sSyn-1 and **P < .003 for Syn-1 versus sSyn-1.