Confocal light micrograph of cancer cells co-stained to visualise actin (purple/brown), an essential component of the cytoskeleton (cells skeleton), and tropomyosin (blue), an actin binding protein that regulates additional binding proteins. It is hypothesised that this mechanism allows a single protein (actin filaments) to play an essential role in many different essential cellular processes. Magnification: x410 when printed at 10 centimetres wide.