RBP4 and metabolic dysfunction-associated steatotic liver disease: Recent advances indicated that some hepatokines, including fetuin-A and fetuin-B [24], hepassocin [25], leucocyte cell-derived chemotaxin 2 (LECT2) [26], follistatin [27], retinol-binding protein 4 (RBP4) [28], selenoprotein P (SeP/Sepp1) [29], and tsukushi (Tsku) [30] promote NAFLD progression, while others, including fibroblast growth factor 21 (FGF21) [31], adropin [32], and growth differentiation factor 15 (GDF15) [33], limit this process [21,22,23].