However, when Ki67 analysis was performed in BPA+/+ and BPA−/− tumors of same size (e.g., Breslow thickness)—either after tumor appearance (≤2 mm), or when tumors reached maximum allowed size (≥ 4 mm)—we did not observe any significant difference between the two groups (Fig. 2c, d), suggesting that BPA+/+ and BPA−/− tumors actually showed similar proliferation rates. Here, MKI67 is linked to neoplasm.