Based on our kinase inhibitor screen described in Figure 3, we discovered that almost all mTOR inhibitors showed inhibitory activity on cyst growth, but most PI3K inhibitors showed at most only mild inhibition, which was unexpected in view of the expected role of PI3K in PKD.22, –24 This was confirmed using PCA-based visualization and showed that mTOR inhibitors blocked the forskolin-induced phenotype, whereas PI3K inhibitors had no effect (Fig. 5A). Here, MTOR is linked to cyst.