Two isoforms of the human cyclin C gene are expressed differentially suggesting that they may have distinct functions.

Cyclin C is a highly conserved protein that is involved in divergent cellular processes. The exact roles of its isoforms are presently not very well defined and it is possible that there is a functional divergence amongst them. We therefore sought to assess the expression pattern of cyclin C1 and C2 isoforms in various human tissues and in cell cycle by using real-time PCR experiments. Our findings strongly suggest that the C2 isoform may play a presently unexplored and important role in mammalian testis and probably this isoform is the one that is mainly implicated in cell cycle regulation.