We tested for an association of CDC42 with intrinsic subtype using the Gallen IHC system [9], whereby Luminal A tumours are defined as ER+, Ki67-low, Luminal B are ER+ and either Ki67-high or HER2+, HER2 tumours are ER−, HER2+, and Negative tumours are ER−, HER2−. Here, ERBB2 is linked to neoplasm.