CRABP1 and neuroblastoma: Moreover, it has been shown that CRABP-I could play a crucial role in differentiation processes in vitro : (i) the up-regulation of CRABP-I in human neuroblastoma cells reduced their differentiation potential [43], (ii) the overexpression of CRABP I in F9 cells decreased their RA-induced differentiation and high concentration of RA become required for this cells to recover the responsiveness to RA, (iii) a reduced level of CRABP I led to a higher RA sensitivity of the cells to differentiate [74], [75].