C1QBP and neoplasm: It is not therefore surprising to find that the proliferative function of tumor cell surface expressed gC1qR can be abrogated by blockade of its C1q binding site, while the proliferative function of cell surface C1q, is abrogated by blockade of the gh (globular head) domains, again confirming that the pro-proliferative function of C1q resides in its gh domains, with the ghA domain playing a central role (28).