Cluster Assignment Cluster Number 1 2 3 4 P53 (p) 2 3 1 - PTPN11-SH2 (pt) 3 - - 3 Src--SH2 (s) 3 1 1 - CDK2 (c) - 1 2 3

Table 6: Cluster assignment for each known protein sample on a specimen of 23 spectra in the ROI 1000/1200 with a binning window of 500 m/Z. Statistics are based on the SpADS results coupled with K Means clustering given in Figure 9.