We developed a dendritic molecular glue (PC)Glue-NBD that can serve universally to "turn on" protein-protein interactions (PPIs) spatiotemporally. (PC)Glue-NBD carrying multiple guanidinium ion (Gu(+)) pendants can adhere strongly to target proteins and cover their surfaces including the PPI interface regions, thereby suppressing PPIs with their receptor proteins. Upon irradiation with UV light, (PC)Glue-NBD on a target protein is photocleaved at butyrate-substituted nitroveratryloxycarbonyl linkages in the dendrimer framework, so that the multivalency for the adhesion is reduced. Consequently, the guest protein is liberated and becomes eligible for a PPI. We found that hepatocyte growth factor HGF, when mixed with (PC)Glue-NBD, lost the affinity toward its receptor c-Met. However, upon exposure of the (PC)Glue-NBD/HGF hybrid to light-emitting diode light (365 nm), the (PC)Glue-NBD molecules on HGF were photocleaved as described above, so that HGF was liberated and retrieved its intrinsic PPI affinity toward c-Met. The turn-on PPI, thus achieved for HGF and c-Met, leads to cell migration, which can be made spatiotemporally with a millimeter-scale resolution by pointwise irradiation with UV light.