RAC1 and neoplasm: In addition, we suggested that signaling perturbation agents (e.g., Y27623, a ROK inhibitor) can be applied to acute or chronic UVR-induced tumor formation/SCC progression displaying upregulation of keratinocyte inflammation and proliferation in order to correct the imbalance between RhoA–ROK signaling and Rac1-PKNγ activation during epidermal dysfunction.