Keep the FMM together with your passport at all times. Under Mexican law, it is your responsibility to ensure the bottom portion of the FMM is returned to the Mexican government at time of departure so that the bar code can be scanned, thus showing that you left the country on time. For example, if you are flying with Aeromexico, they may ask for your passport and FMM at check-in for your flight home, then staple your FMM to your boarding pass. You are expected to then hand the boarding pass together with your FMM to the gate agent as you board your flight. If you lose your FMM during your visit to Mexico, you may be subject to substantial delays and a MXN500 fine before you can leave the country.
Corticosteroids have been used as drug treatment for some time. Lewis Sarett of Merck & Co. was the first to synthesize cortisone, using a complicated 36-step process that started with deoxycholic acid, which was extracted from ox bile .  The low efficiency of converting deoxycholic acid into cortisone led to a cost of US $200 per gram. Russell Marker , at Syntex , discovered a much cheaper and more convenient starting material, diosgenin from wild Mexican yams . His conversion of diosgenin into progesterone by a four-step process now known as Marker degradation was an important step in mass production of all steroidal hormones, including cortisone and chemicals used in hormonal contraception .  In 1952, . Peterson and . Murray of Upjohn developed a process that used Rhizopus mold to oxidize progesterone into a compound that was readily converted to cortisone.  The ability to cheaply synthesize large quantities of cortisone from the diosgenin in yams resulted in a rapid drop in price to US $6 per gram, falling to $ per gram by 1980. Percy Julian's research also aided progress in the field.  The exact nature of cortisone's anti-inflammatory action remained a mystery for years after, however, until the leukocyte adhesion cascade and the role of phospholipase A2 in the production of prostaglandins and leukotrienes was fully understood in the early 1980s.