Confocal light micrograph of cancer cells co-stained to visualise actin (red), an essential component of the cytoskeleton (cells skeleton), and tropomyosin (magenta), 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.