Before revision:  We conclude with an algorithm that maintains a 2-approximate MAX-IS for dynamic sets of uniform height and arbitrary width rectangles with O(\omega \log n) update time, where \omega is the largest number of maximal cliques stabbed by any axis-parallel line}  .
After revision:  We conclude with an algorithm that maintains a 2-approximate MAX-IS for dynamic sets of uniform height and arbitrary width rectangles with O(\omega \log n) update time, where \omega is the largest number of maximal cliques stabbed by any axis-parallel line} and 4 and corresponding running-time trade-offs .