Instead, there is a positive correlation between the co-expression of GRB7 and KIT (a gene encoding the v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog receptor, another tyrosine kinase receptor that interacts with Grb7 and which maps at the locus 4q11-q12) in seminomas, but not in non-seminoma testicular tumors. Here, NTRK1 is linked to seminoma.