Table 2.

Proteins involved in the regulation of neurite elongation with the corresponding KO/KD phenotypes.

Protein	Gene Mutation (1)	Phenotype	Reference
Rac1	Forebrain-specific KO	Increased number of primary neurites and secondary branches	[95]
RhoA	KO	Increased axon length (significantly greater actin retrograde flow, fewer actin arcs, and substantially longer F-actin bundles)	[368]
Cdc42	KO	Defective axon formation (disrupted cytoskeletal organization, enlargement of the growth cones, and inhibition of filopodia dynamics)	[97]
WAVE1	KO	No effect on neurite growth	[369]
Cdk5	Dominant-negative	Inhibition of neurite outgrowth	[370]
p35	KD	Inhibition of neurite outgrowth	[370]
Arp2/3	KD	Increased number of irregular, shorter, and broader neurites	[371]
PAK1	Dominant-negative	Decreased number of dendrites	[361]
PAK2	Dominant-negative	No effect on the neurite growth	[372]
PAK3	KD	Increased elongation of neuronal processes	[373]
LIMK2	KD	Reduced number of neurite-bearing cells and the mean neurite length	[222]
LIMK1	KD	Reduced number of neurite-bearing cells and the mean neurite length	[222]
ROCK1	Haploinsufficiency	Increased basal and apical dendritic length and dendritic intersections	[374]
ROCK2	Haploinsufficiency	No effect on the neurite growth	[374]
SSH1/SSH2	KD	Decreased neurite extension	[222]
ArhGEF6	KO	Increased neurite length	[184]
ArhGEF7	Cortex-specific KO	Impaired axon formation	[193]
ArhGAP15	KO	Decreased neurite length and branching	[172,375]
TRIO	Neuron-specific KO	Decreased axon length	[376]
Tiam1	KO	Decreased neurite length	[211]
NOMA-GAP	KO	Decreased dendritic branching	[176]
OPHN1	KO	Decreased dendritic tree complexity, i.e., branching	[377]
Cofilin	KO	Inhibited neurite outgrowth	[378]
Profilin1	KD	Impaired axon elongation	[349]
Profilin1	Mutation of the actin-binding domain	Decreased of neurite length	[265]
Formin	KO	Impaired axon elongation	[379]
Shootin1	KD	Inhibited polarization	[380]

(1) Gene mutations referred to in in vitro and in vivo models.