For instance, studies on spinocerebellar ataxia type 1 (SCA1) suggest a reciprocal relationship between PP2A and ataxin-1, whereby PP2A dephosphorylates ataxin-118 and ataxin-1 modulates PP2A activity and holoenzyme composition in Purkinje cells.19 This evidence concerns the gene ATXN1 and spinocerebellar ataxia type 1.