Moreover, although LIMK1's upstream activator in neurons is unclear, spine abnormalities and intellectual impairments are also linked to mutations in PAK3 (Allen et al., 1998; Boda et al., 2004), a member of the p21-activated kinase (PAK) family that phosphorylates and activates LIMK1 in non-neuronal cells (Edwards et al., 1999). The gene discussed is LIMK1; the disease is Cognitive impairment.