CHK-1 phosphorylation in germ cells was greatly reduced in a
wrn-1(
gk99) mutant (and also after RNAi-mediated
wrn-1 knockdown, data not shown) and after
atl-1 RNAi. The dependence of CHK-1 phosphorylation on WRN-1 and ATL-1 after DNA replication inhibition was also confirmed by Western blotting of worm extracts with the pSer345 CHK1 antibody, indicating that CHK-1 phosphory- lation is reduced in
wrn-1 and
atl-1 in the extracts.