The function of Ensembl gene identifier ENSG00000139116 (KIF21A, kinesin family member 21A) is as follows. Processive microtubule plus-end directed motor protein involved in neuronal axon guidance. Is recruited by KANK1 to cortical microtubule stabilizing complexes (CMSCs) at focal adhesions (FAs) rims where it promotes microtubule capture and stability. Controls microtubule polymerization rate at axonal growth cones and suppresses microtubule growth without inducing microtubule disassembly once it reaches the cell cortex. {ECO:0000250|UniProtKB:Q9QXL2, ECO:0000269|PubMed:24120883}.