Using a combination of luminescent and fluorescent sdAbs, this recent preprint describes the detection of endogenous CXCR4 clusters by BRET. This receptor clustering is increased upon enhanced expression in cancer cells and has been linked to cancer progression.
This work has been a collaboration of researchers from Martine Smit’s group at the VU, the AUMC, and QVQ and is now online:
https://www.biorxiv.org/content/10.1101/2024.12.06.627249v1

QVQ offers CXCR4-targeting sdAbs as well as various modifications via fusions and conjugations.