Recently, human HD patient cells and mouse (Q140/Q140) striatum and primary neurons were shown to be less sensitive to growth factor stimulation and this reflected a disruption of a Rac1:p85(PI3K):α-actinin-2 complex (e.g. the mHTT does not interact with p85), which is enriched in striatal neurons and spines (Tousley et al. 2019). This evidence concerns the gene RAC1 and Huntington disease.