"Because
lin-17 and
lin-18 single mutants displayed partially penetrant defects in POP-1 localization, we examined whether the
lin-17 and
lin-18 genes had redundant functions in regulating POP-1. We found that animals that were doubly mutant for
lin-17(
n671) and
lin-18(
e620) displayed an enhanced rate of defects in POP-1 localization compared to either single mutant (Fig. 3; Table 1). This enhancement is particularly notable for the sisters P7.paa and P7.pap, which normally localize POP-1 in a low/high pattern. In
lin-17(
n671) or
lin-18(
e620) single mutants, these sisters localized POP-1 in the reversed high/low pattern in a low number of cases (7 of 35 and 0 of 38, respectively). However, in double mutants, these sisters displayed the reversed high/ low pattern in most cases (29 of 30 specimens). Double mutants also displayed POP-1 localization defects in the posterior half of the P6.p lineage. The sisters P6.ppa and P6.ppp most often localized POP-1 in a low/high pattern in wild-type and single mutants. However, in double mutants, these sisters most often localized POP-1 in the reversed high/ low orientation (21 of 30 specimens)."