BRCA1 and breast cancer: Through this technology, researchers have discovered that the cyclin-dependent kinase inhibitor 2A (CDKN2A) gene was a key driver in carcinogenesis, which led to abnormally rapid cell division and might become an early diagnostic marker for breast cancer.263 Additionally, CRISPR/Cas9 gene editing as well as overexpression experiments have also confirmed that the BRCA1-delta11q optional splice isoform is a primary factor in PARPi and cisplatin treatment resistance in breast cancer.264