MERTK and rheumatoid arthritis: While the role of GAS6/MerTK axis in the fibroblast–macrophage crosstalk remains incompletely explored in RA, it is well established in fibrosis and in the tumour microenvironment, where cancer-associated fibroblasts produce abundant amounts of GAS6 with anti-inflammatory effects that promote cancer survival and migration (reviewed in detail in [344])