MBL2 and plasma cell myeloma: Considering that the inhibitory effect of serglycin isolated from multiple myeloma cells started from the very first steps of the classical and lectin pathways, and this was attributed to the binding of serglycin to C1q in the classical and MBL in the lectin pathway [13], we investigated the binding capacity of serglycin isolated from MDA-MB-231 cells to these complement components.