Malignant fibrous histiocytoma amplified sequence 1 (MFHAS1 or MASL1), a member of the ROCO protein family, is a predicted oncoprotein in malignant fibrous histiocytomas (MFHs), gastrointestinal tumors, and B-cell lymphoma [19–21]. Here, MFHAS1 is linked to histiocytoma.