The answer is muscle cell ... has proteins that slide back and forth.
A muscle cell has proteins that slide back and forth. This way the cell contraction occurs. For example, the actin filaments in cell constantly grow and shrink. The two ends of actin filament have different dynamics of addition and removal of subunits. That way, one end of actin filament will grow and one end will shrink so it seems like the filament is moving back and forth.
