Data for plot comes from datasets package. Name of the dataset is "Puromycin" and it represents reaction velocity versus substrate concentration in an enzymatic reaction involving untreated cells or cells treated with Puromycin.

##   conc rate   state
## 1 0.02   76 treated
## 2 0.02   47 treated
## 3 0.06   97 treated
## 4 0.06  107 treated
## 5 0.11  123 treated
## 6 0.11  139 treated