Identification of endogenous peptides in the conditioned media by LC-MS/MS according to the total number of unique peptides and spectral counts.

The HaCaT and SCC-9 cells were treated with PMA for 24 h, the media were collected and the endogenous peptides were analyzed by LC-MS/MS. The total numbers of the unique peptides and the number of spectral counts are shown in bold and the number of spectral counts is shown for each sequence. There is a statistically significant difference in the number of spectral counts of syndecan-1 fragments between SCC-9 cells and SCC-9 cells treated with PMA (Mann-Whitney test, p = 0.0273).