IGF2BP3 and rheumatoid arthritis: However, the specific mechanism of IGF2BP3 in RA has not been elucidated.20 In RA, RA-FLS are characterized by anchorage-independent proliferation, contact inhibition of damage, invasion and metastasis.39 Considering the similarity between FLS and transformed tumor cells, we examined the expression of IGF2BP3 and RASGRF1 in RA and non-RA synovial tissues.