Serine/threonine-protein kinase that may function as a signaling receptor of extracellular matrix component. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Preferentially expressed in roots and flowers. The EGF-like region is specific to this family of proteins and seems to consist of the C-terminal of an EGF-like domain fused to the N-terminal of another one. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.