TSC2 and breast cancer: As a complementary approach, we used proximity ligation assays (PLA), which can quantitatively visualize proteins that are within tens of nanometers of each other as fluorescent puncta in situ.53, 54 PLA in MDA-MB-231 highly metastatic breast cancer cells yielded robust puncta and corroborated the results obtained by immunoprecipitation indicating interactions between endogenous Dock7 and TSC1, TSC2, and mTOR (Figure 1C).