NGC 7538 is a relatively nearby region of high-mass star formation and an excellent place to search for the precursors of future high-mass stars. It shows some interesting structures, including a large ring visible surounding an IRDC. Fallscheer et al. (2013) report no obvious O and B stars that may cause the ring structure (i.e., blowing a bubble into the cloud). There is only an A0 star within the ring and the nearst known B star is east of the ring. Given the lack of suitable stars at the bubble center, the fact that CO observation shows that the bubble is closed, and the elongated nature of the bubble, Fallscheer et al. suggest that bubble is breaking out of the molecular cloud to the south west.