SPOCK1, 2, and 3 are considered matricellular proteoglycans without a structural role. Their functions are only partly elucidated. SPOCK1 was detected in the brain as a member of the neural synapses, then in the neuromuscular junctions. It plays a role in the regulation of the blood-brain barrier. Its best-characterized activity was its oncogenic potential discovered in 2012. Its deleterious effect on tumor progression was detected on 36 different types of tumors by the end of 2020. However, its mode of action is still not completely understood. Furthermore, even less was discovered about its physiological function. The fact that it was found to localize in the mitochondria and interfered with the lipid metabolism indicated that the full discovery of SPOCK1 is still waiting for us.