LDN-211904 acts as an inhibitor of the EphB3 receptor tyrosine kinase. It increases the inhibition of EphB3 kinase by preserving the 2-chloroaniline group and adding either a phenyl or a small electron donor substituent to the 5 position of pyrazole and [1,5-a] pyridine. LDN-211904 serves as a molecular probe for investigating the function and signaling pathways of EphB3 receptors, particularly within the nervous system throughout neurodevelopment and adulthood.