The present invention provides a cell which comprises； (i) a chimeric antigen receptor (CAR) which comprises an antigen binding domain and an intracellular signalling domain； (ii) a membrane tethering component (MTC) which comprises a first dimerization domain； and (Hi) a signal-dampening component (SDC) comprising a signal-dampening domain (SDD) and a second dimerization domain which specifically binds the first dimerisation domain of the membrane-tethering component. Dimerisation between the MTC and SDC may be controllable with an agent, meaning that the agent can be used to control CAR-mediated cell signalling.
