PARP1 and breast cancer: Using the TIMER 2.0 database, we analyzed the expression levels of these six genes at the pan-cancer level, and the results were as follows: BIRP1, PARP1, and RFC4 were significantly overexpressed in BRCA (Breast cancer), BLCA (Bladder Urothelial Carcinoma) and LIHC (Liver hepatocellular carcinoma) while they were significantly lower expressed in KICH (Kidney Chromophobe).