Take a look on my chart(sticky), you will see what is the ADX line(white) and the +DI line(green), the white line works as a resistance to the green one, and stop the stock from running, because when the green line breaks the white one, a buy signal is generated.
About the RSI70 line, take a look on the the chart below, a daily chart, you can see that the stock is almost touching there, this line is the beginning of the overbought zone, and usually also works as a resistance to any stock.