**Figure 2. **VEGFA_{165}a strongly activates MAPK in primary HRMECs at doses where VEGFA_{165}b has little effect. Activation of MAPK was measured with in situ immunofluorescence with a phosphospecific antibody (phospho-Thr202/Tyr204)
for p44/42. **A**: Activation of MAPK at three time points after the addition of 1,000 pM VEGFA_{165}a or VEGFA_{165}b. Bar shows standard deviation. (*t* test, ***p<0.001 relative to untreated control, n=8 biologic replicates.) **B**: Dose–response curves for activation of MAPK. The median effective dose (ED_{50}) was 73 pM for VEGFA_{165}a and 1,015 pM for VEGFA_{165}b. Bars indicate the 95% confidence interval for data fit to the four-parameter log-logistic function. n=4 biologic replicates
per dose.