rtPCR and Western blotting were used to determine which members of the PKC family are present in both immature and mature mouse oocytes. Using isoform-specific PCR primers and antibodies PKC-δ and -λ were detected while such techniques failed to observe the conventional isoforms of PKC-α, -β, -γ. This isoform profile was confirmed using an alternative PCR strategy, which allowed discrimination of PCR products derived from conventional and novel PKC isoforms. In addition PKC-ε, -η, -θ and -ζ were not detected by rtPCR. These results suggest that the predominant isoforms in oocytes are PKC-δ and -λ.