请教significant redundancy 在句中的意思

我看到一篇英文文献中讲到细胞因子时这样写道：Cytokines are produced in response to diverse cellular stimuli and serve as growth factors and regulators of the immune response . They act on multiple cell types with significant redundancy in their actions.我实在不能理解significant redundancy 在句中是什么意思？
请教一下大家！谢谢！