EGFR and head and neck squamous cell carcinoma: To understand how cell size and other factors can confound mass cytometry data and especially analyses of cellular responses, we perturbed cells from the HNSCC Cal33 cell line using EGF stimulation (30 min), EGFR inhibition (Gefitinib, 24 h), Etoposide treatment (2 h), IFN-β stimulation (30 min), IGF stimulation (30 min), PI3K inhibition (24 h), and starvation alone (24 h).