SGC-CK2-2 is a highly potent and selective casein kinase 2 (CK2, CKII) inhibitor (IC50 = 3 nM/CK2α and <1 nM/CK2α by enzyme assay; CK2α/CK2αμ IC50 = 920/200 nM by cellular NanoBRET; genomewide by DiscoverX scanMAX panel at 1 μM). SGC-CK2-2 effectively inhibits CK2 downstream signaling in MDA-MB-231 cells (AKT pS129 IC50 ~5 μM post 24h) without cytotoxicity (up to 10 μM & 48h).