The primary molecular classification marker exhibited higher variability than other classification markers in two of the cancer cell lines (HER2: σSK-BR-32=2.08 × 1012, n=27, ER: σMCF72=1.24 × 1015, n=35; EGFR: σBT-202=3.15 × 1011, n=27). Here, ESR1 is linked to cancer.