Kolon TissueGene, a subsidiary of Kolon Life Science, said Co-CEO Lee Woo-sok resigned as of Wednesday.

Lee’s departure leaves Noh Moon-jong as the sole CEO of Kolon TissueGene. Lee stepped down as a director of the board at Kolon TissueGene as well.

“Lee Woo-sok decided to focus on Invossa issues as CEO of Kolon Life Science, and let Kolon TissueGene CEO Noh Moon-jong concentrate on resuming a clinical trial (on Invossa) in the U.S. It was for an efficient decision making,” an official at Kolon TissueGene said.

Earlier, the regulator suspended the sales of Invossa-K, gene therapy for osteoarthritis, after finding out that Kolon has mislabeled one of the cell ingredients over a decade.

The trading of Kolon TissueGene shares has been suspended due to the need for a review over the company’s eligibility for KOSDAQ listing.

The KOSDAQ Market Committee is scheduled to decide on whether Kolon TissueGene is subject to the review of eligibility for KOSDAQ listing by June 19.