Researchers have identified control elements of a new tumor suppressor gene (TS) that regulates cell division. They do a screen to identify chemicals that increase the rate of transcription of this TS gene. They compare the mean rates of cell division in wildtype cells (WT) and cells treated with chemical X. They are interested in determining whether there is a decrease in mean cell growth in TS cells compared to WT cells. What types of statistical test should they conduct?
1) 2-tailed, independent t-test
2) 2-tailed, paired t-test
3) 1-tailed, independent t-test
4) 1-tailed, paired t-test