PKN3 and dopa-responsive dystonia due to sepiapterin reductase deficiency: To test the assumed ability of PKN3 to phosphorylate p130Cas, we prepared a GFP‐fused p130Cas mutant for Ser432 (S432A) and p130Cas mutated in SRD in such a manner that all 15 Ser/Thr sites were substituted with Ala or Asn (15AN).