RAD18 and lung adenocarcinoma: The GEPIA database prediction results showed positive correlations between the expression of Rad18, PCNA, RPA32 and that of SERTAD2 in lung adenocarcinoma; indeed, the correlation between Rad18 and SERTAD2 was the most significant (R = 0.46, P < 0.0001) (Fig. 6B).