For example, USP1 deubiquitinates FANCD2/FANCI or PCNA to prevent the recruitment of interstrand crosslink repair proteins and translesion DNA polymerase to inhibit DNA repair; USP7 regulates lung squamous cell carcinoma cell proliferation through MEK/ERK signaling by deubiquitinates the Raf-1 [175,176]. Here, PCNA is linked to squamous cell lung carcinoma.