CSF extract was supplemented with Myc-XErp1 DSG- DSA- ZBR- (S33N S38N S284N S288N C583A) IVT that was either wild-type or mutated to alanine at the p90RSK-target sites S335, T336 and S342 (Rsk3A). Both reactions were divided and treated with DMSO or CsA. Calcium was added and samples were taken at the indicated time points. Samples were immunoblotted for the Myc-tag and cyclin B2. The cyclin B2 membrane was stripped and reprobed for α-tubulin. Asterisk indicates unspecific bands. 