title: Superscript/subscript in R
body: <p>I would like to have on a plot the following:</p>
  
  <p><a href="https://i.stack.imgur.com/Rf5Ez.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Rf5Ez.png" alt="enter image description here"></a></p>
  
  <p>I am using this code, but I don't get the expected outcome.</p>
  
  <pre><code>text(4.4,0.5, expression(paste(P[B6.Rag^"-/-"_NOD.Rag^"-/-"], "=2.9x10^-4")), cex = 1.3)
  </code></pre>
  
  <p>Thanks</p>