Bafilomycin A1, a macrolide antibiotic that has been demonstrated to inhibit vacuolar type H+-ATPase, inhibits endosomal and lysosomal acidification and blocks lysosomal degradation of EGF in A431 cells (human epidermoid carcinoma cells) (Yoshimori et al, 1991; Melikova et al, 2001), blocked degradation of 125I-EGF in KB-3-1 cells. Here, EGF is linked to squamous cell carcinoma.