With respect to the roles of heterotrimeric and small G-proteins in neurite retraction, it has been shown that GPCR agonists that activate Gα12, Gα13 or small G-protein, Rho, can cause similar neurite retraction in primary cultured hippocampal neurons, PC12 cells or N1E-115 neuroblastoma cells. This evidence concerns the gene RHO and neuroblastoma.