UBXN-2 regulates AIR-1 mobile fraction in prophase. (A) AIR-1 coimmunoprecipitates with UBXN-2. The immunoprecipitation was split in two and ran in two independent gels because AIR-1 and UBXN-2 migrate at the same level (∼37 kD). (B) AIR-1 coimmunoprecipitates with CDC-48. (C) Quantification of the spindle misorientation phenotype of ubxn-2(ok1942)/+ embryos depleted for UBXN-2, AIR-1, or both. air-1(RNAi) embryos did not form a spindle (Hannak et al., 2001). **, P < 0.01 for the difference between ubxn-2(RNAi) and ubxn-2(RNAi)/air-1(RNAi) embryos (χ² test). Embryonic lethality was 77.7% ± 6.54 for ubxn-2(RNAi), 97.7% ± 3.42 for air-1(RNAi), and 84.1% ± 4.76 for ubxn-2(RNAi);air-1(RNAi). (D) Percentage of mobile fraction of AIR-1 estimated by FRAP. The strain used (OD142) expresses GFP::AIR-1. Histograms represent the mean (±SEM) of the five last points of each FRAP curve for the indicated cell cycle time. (E–G) FRAP results of control or ubxn-2(RNAi) GFP::AIR-1 at the indicated cell cycle time. The experimental mean values of FRAP ± SEM are presented in light green and red, respectively; the fitted curves are in dark green and red, respectively. Curves were fitted following the equation described in Materials and methods. The R² values indicate the correlation coefficient obtained by fitting experimental curves to the model. The t_1/2 represents FRAP half time. (H) Percentage of mobile fraction of SPD-2 estimated by FRAP, in control and ubxn-2(RNAi) embryos. The strain used (TH42) expresses GFP::SPD-2. Histograms represent the mean (±SEM) of the five last points of each FRAP curve for the indicated cell cycle time.