To study the inducible regulation of GANP DNA-primase during cell activation, we examined phosphorylation induced by various kinds of kinases.We observed that the cell cycle-associated kinase Cdks induced phosphorylation of GANP in vitro. Examination of immunoprecipitates of Cdk2 from B cells revealed phosphorylation of GANP-PD at a consensus sequence of Cdk phosphorylation at Ser502 (S/T-P-X-K/R) (Fig. (Fig.1C1C Left; ref. 22).