Teacher:In this task, you are given a sentence. You are expected to recognize the name of gene or protein. Although there might be several correct answers, you need to write one of them.
Teacher: Now, understand the problem? Solve this instance:  The stroma as the necessary target for endocrine mammogens and the source of stimulatory growth factors is described and the importance of mammary epithelium - induced modifications of the periductal stroma is emphasized .
Student:
growth factors