Catharanthus roseus Receptor-Like Kinase 1-like (CrRLK1L) family proteins are considered as potential cell wall sensors in plants. CrRLK1L subfamily proteins harbor two extracellular malectin-like domains that may bind to cell wall polymers, and an intracellular kinase domain that transmits signals via the phosphorylation of intracellular substrates. In Arabidopsis, there are 17 CrRLK1L family members, among which FER is the most widely studied. A growing body of evidence support that FER not only regulates plant growth and development, such as root hair development, pavement cell morphogenesis, flowering, and fertilization, but also controls plant responses to biotic and abiotic stresses. To decipher molecular mechanisms underlying the FER-mediated regulation of plant growth and development, we performed an immunoprecipitation-mass spectrometry (IP-MS) assay using FER-GFP transgenic plants to search for FER-interacting proteins.