Fig 7. PRRG4 lowers rRobo1 protein levels in COS cells.

COS cells were transfected with plasmids encoding either rRobo1 or hDscam and increasing amounts of PRRG4. A. Immunoblot analysis of hDscam and rRobo1 proteins levels in the presence of different amounts of PRRG4. Rat Robo1 protein levels fall with increasing amounts of PRRG4 plasmid, whereas hDscam levels remain relatively constant. B. Quantification of independent immunoblot experiments. The density of protein bands for hDscam and rRobo1 was quantified using ImageJ. The positive control was each plasmid transfected in the absence of PRRG4 plasmid and this densitometric value was set at one. All other values for each experiment were expressed as value relative to the control to normalize across different experiments. The values were analyzed in a one-way ANOVA with a Fisher LSD test. Asterisks represent p values for differences between hDscam and rRobo1, * p < 0.05, ** p < 0.01, *** p < 0.001. For 120ng of PRRG4, the difference was not statistically significant (p = 0.05118) but was clearly trending towards significance. The effect for 250ng PRRG4 was very strong and reproducible (p = 0.00002). Error bars represent standard error and are obscured by the 250ng PRRG4 data point for the dashed rRobo1 line. The underlying data are shown in S3 Data.