Further studies, including microarray analysis of the original and transplanted tumors, as well as transplantation experiments in which p190B+/-Neu mammary epithelium is introduced into wild-type stroma and is allowed to go through the stochastic process of tumor formation, will be required to fully understand the contribution of p190B in the epithelium to tumor initiation, growth, and progression. Here, ERBB2 is linked to neoplasm.