There are 20 different R groups, and so 20 different amino acids. Since each R group is slightly different, each amino acid has different properties, and this in turn means that proteins can have a wide range of properties. The following table shows the 20 different R groups, grouped by property, which gives an idea of the range of properties. You do not need to learn these, but it is interesting to see the different structures, and you should be familiar with the amino acid names. You may already have heard of some, such as the food additive monosodium glutamate, which is simply the sodium salt of the amino acid glutamate. Be careful not to confuse the names of amino acids with those of bases in DNA, such as cysteine (amino acid) and cytosine (base), threonine (amino acid) and thymine (base). There are 3-letter and 1-letter abbreviations for each amino acid.
The number of players who have admitted using steroids in a confidential survey conducted by the NCAA since the 1980s has dropped from percent in 1989 to percent in 2003.  During the 2003 season, there were over 7,000 drug tests, with just 77 turning up as positive test results.  Scukanec claims that methods were used to get around the drug testing, whether it be avoiding the tests by using the drugs during the off-season, or flushing the drugs out of your system. This was used with a liquid he referred to as the "pink."  He stated:
Bortezomib, a boronic acid dipeptide, is a highly selective, reversible inhibitor of the 26S proteasome which primarily functions in the degradation of mis-folded proteins and is essential for the regulation of the cell cycle. Exposure to Bortezomib has been shown to stabilize p21, p27, and p53, as well as the proapoptotic Bid and Bax proteins, caveolin-1, and inhibitor κB-α, which prevents activation of nuclear factor κB-induced cell survival pathways. Bortezomib also promotes the activation of the proapoptotic c-Jun-NH2 terminal kinase, as well as the endoplasmic reticulum stress response. Alteration of the levels of these cellular proteins leads to inhibition of proliferation, migration, and promotion of apoptosis of cancer cells.  Bortezomib is shown to penetrate into cells and inhibit proteasome-mediated intracellular proteolysis of long-lived proteins with a concentration that inhibits 50% of the proteolysis of ∼ μM. The average growth inhibition of 50% value for Bortezomib across the entire panel of 60 cancer cell lines derived from multiple human tumors from the US National Cancer Institute (NCI) is 7 nM. Treatment of PC-3 cells with Bortezomib (100 nM) for 8 h results in the accumulation of cells in G2-M, with a corresponding decrease in the number of cells in G1. Bortezomib kills PC-3 cells at 24 and 48 hr with IC50 of 100 and 20 nM, respectively. Bortezomib induces nuclear condensation at 16–24 hr after treatment. Bortezomib treatment leads to PARP cleavage in a time-dependent manner with concentrations as low as 100 nM being effective at 24 hr.