CASK and focal segmental glomerulosclerosis: Notably, within the past five years, a prospective study has elucidated the role of monocytes and M2 macrophages in secreting calcium/calmodulin-dependent serine/threonine kinase (CASK) via exosomes, impacting the integrity of the glomerular filtration barrier within focal segmental glomerulosclerosis (FSGS) kidneys35.