The results of the study conducted by Sasano et al. (21 invasive duct carcinomas and 19 invasive lobular carcinomas) showed that there was no significant difference in the means of the labelling indexes of Ki67, cyclin D1, cyclin E, cdk2, cdk4, oestrogen receptor and progesterone receptor status in invasive ductal and lobular carcinomas [9]. Here, CDK4 is linked to invasive lobular breast carcinoma.