Given an abstract, indicate which of the provided candidate titles (Option1 and Option2) best describes it (respond with the text of the title, not option1/2).

Abstract: A 52K glycoprotein is secreted by human breast cancer cells in culture after estrogen stimulation. Using monoclonal antibodies, we have quantitated and characterized the corresponding proteins of the cell compartment. Using pulse-chase experiments, we have shown that about 40% of the 52K protein is secreted, the majority being successively processed into a 48K and a 34K protein. This last protein is very stable. The processing is inhibited by lysosomotropic agents and leupeptin, suggesting that it occurs in acidic vesicles, such as lysosomes or endosomes. Estradiol increased the intracellular level of immunoreactive 52K related proteins by 4-fold. Its effect is, however, more obvious in the medium, since there is a constitutive level in the cell. The stimulatory effects of estradiol on [3H]mannose and [35S]methionine incorporation into these proteins were similar and the endoglycosydase H sensitivity of the proteins was not altered, suggesting that estradiol did not modulate the glycosylation step. Antiestrogens did not stimulate synthesis and glycosylation of the 52K related proteins. Estradiol also increased the stability of the 52K precursor as well as that of total proteins. We conclude that the secreted 52K protein is the precursor of two cellular proteins of 48K and 34K. Estradiol stimulates both the intracellular accumulation of these proteins and the secretion of the precursor.
Which is the apt title for the abstract? option1: Processing and estrogen regulation of the 52-kilodalton protein inside MCF7 breast cancer cells. option2: Nasal endoscopes in hypophysectomy [letter]
Processing and estrogen regulation of the 52-kilodalton protein inside MCF7 breast cancer cells.