Steroid isolation , depending on context, is the isolation of chemical matter required for chemical structure elucidation, derivitzation or degradation chemistry, biological testing, and other research needs (generally milligrams to grams, but often more  or the isolation of "analytical quantities" of the substance of interest (where the focus is on identifying and quantifying the substance (for example, in biological tissue or fluid). The amount isolated depends on the analytical method, but is generally less than one microgram.  [ page needed ] The methods of isolation to achieve the two scales of product are distinct, but include extraction , precipitation, adsorption , chromatography , and crystallization . In both cases, the isolated substance is purified to chemical homogeneity; combined separation and analytical methods, such as LC-MS , are chosen to be "orthogonal"—achieving their separations based on distinct modes of interaction between substance and isolating matrix—to detect a single species in the pure sample. Structure determination refers to the methods to determine the chemical structure of an isolated pure steroid, using an evolving array of chemical and physical methods which have included NMR and small-molecule crystallography .  :10–19 Methods of analysis overlap both of the above areas, emphasizing analytical methods to determining if a steroid is present in a mixture and determining its quantity. 
Granulosa cells express the closely related orphan nuclear receptors steroidogenic factor-1 (SF-1) and liver receptor homolog-1 (LRH-1). To determine whether SF-1 and LRH-1 have differential effects on steroid production, we compared the effects of overexpressing LRH-1 and SF-1 on estrogen and progesterone production by undifferentiated rat granulosa cells. Adenovirus mediated overexpression of LRH-1 or SF-1 had qualitatively similar effects. Neither LRH-1 nor SF-1 alone stimulated estrogen or progesterone production, but when combined with FSH and testosterone, each significantly augmented progesterone production and mRNAs for cholesterol side-chain cleavage enzyme and 3beta-hydroxysteroid dehydrogenase above that observed with FSH alone, with SF-1 being more effective than LRH-1. LRH-1 did not augment FSH-stimulated estrogen production, whereas SF-1 produced only a slight ( approximately 30%) augmentation of FSH-stimulated estrogen production. The stimulatory actions of both were reduced by overexpression of dosage-sensitive sex reversal, adrenal hypoplasia congenita, critical region on the X chromosome, gene 1. Expression of either LRH-1 or SF-1 together with constitutively active protein kinase B in the absence of FSH stimulated progesterone production and mRNAs for 3beta-hydroxysteroid dehydrogenase and cholesterol side-chain cleavage enzyme but did not stimulate estrogen production or mRNA for aromatase. These findings demonstrate that LRH-1 and SF-1 have qualitatively similar actions on FSH-stimulated estrogen and progesterone production, which would suggest that these factors may have overlapping actions in the regulation of steroidogenesis that accompanies granulosa cell differentiation.