Also, cell-impermeable analogues of E2, such as E2-BSA and E2-peroxidase, induce a rapid increase in intracellular calcium levels and prolactin release in both normal and tumor anterior pituitary cells [11], [38], [61] Prolactin release is also stimulated by ERα-specific antibodies which are too large to enter the cell, indicating the presence of an active extracellular domain in the mERα able to transduce estrogenic signals from the plasma membrane [62]. This evidence concerns the gene PRL and neoplasm.