Correction to: Cell Research (2018) 28:1; https://doi.org/10.1038/s41422-018-0095-6; published online 18 October 2018.
We apologize for an error introduced during format conversion in the paper published online on 18 October 2018. The resolution of the MALDI-TOF result in Fig. 1e underwent an unexpected reduction when transformed from Powerpoint format. The corrected Fig. 1e is provided below.