Firstly, according to whether the RBC is marked or not, a rod-shaped or cone-shaped BC is divided; secondly, according to the bipolar mark Isl1 and/or Grm6, the cone BC cluster can be further divided into on (3–6, 13, 15) and off (7–10, 12, 14) BC type. This evidence concerns the gene ISL1 and breast cancer.