There is a dilemma in clarifying the role of HAPLN1 in RA-FLSs viability by functional studies in the cancer research field because an increased level of HAPLN1 seems to be associated with a higher degree of aggressiveness, leading to stemness of various cancers (47, 48, 57) while achieving robust ECM restrictions on metastasis of cancer cells (19, 20). This evidence concerns the gene HAPLN1 and cancer.