The focus of his research group is on the genetic dissection of human breast cancer through the use of Cre/loxP-based mouse models for p53-mutated breast cancer, BRCA1- and BRCA2-associated hereditary breast cancer, and E-cadherin-mutated invasive lobular breast cancer. These models are used to (i) investigate genotype-phenotype relations in mammary tumorigenesis; (ii) identify genetic changes underlying breast carcinogenesis; (iii) assess the role of tumor-initiating cells in breast cancer metastasis and therapy resistance (iv) study the role of inate and adaptive immunity in breast cancer development; (iv) study therapy response and drug resistance in specific breast cancer subtypes.