Phospho-LRP6 (Ser1490) is a key phosphorylation site on the LRP6 protein, which is a component of the Wnt-Fzd-LRP5-LRP6 complex that initiates the β-catenin signaling pathway. This phosphorylation event is crucial for the aggregation of receptor-ligand complexes into ribosome-sized signalsomes, which are essential for the activation of the Wnt/β-catenin signaling. The phosphorylation of LRP6 at Ser1490, mediated by kinases such as GSK3 and CK1, is required for the binding of AXIN1 and subsequent stabilization and activation of β-catenin by preventing GSK3-mediated phosphorylation of β-catenin. This process is pivotal in various biological processes, including bone formation and embryonic development. The Phospho-LRP6 (Ser1490) antibody specifically detects endogenous levels of LRP6 only when it is phosphorylated at Ser1490, indicating the importance of this modification in the regulation of Wnt signaling.