*4.11. Tube Formation Assay*

Tube formation assays were performed as previously described with minor modifications [106]. 150 µL of Matrigel (Fisher Scientific CB40234A) was used to coat wells of a 24-well plate and solidified at 37 ◦C for 1–2 h. Cells were seeded at a density of 75,000 cells/well in RPMI-1640 media, 48 h after treatment with the *PLAGL1* siRNA or a scrambled control. Images were taken after 10 h of incubation on the Matrigel using light microscopy from three random fields of each well. Cord formation ability was calculated by counting the number of meshes and the total branch length using the Angiogenesis Analyzer plugin from ImageJ.
