ch5E6 specifically recognized high molecular weight (>250 kDa) endogenous forms of MUC16 in pancreatic cancer (SW1990, T3M4, COLO357, and CD18) (Fig. 2a–I, upper panel) and lung cancer (SW1573, H2122) (Fig. 2b-I, upper panel) cell lines and the cleaved low molecular weight forms (~17 kDa) of MUC16 (Fig. 2, a-I and 2b-I, lower panel) as compared to no reactivity in MUC16 negative PC (MIA PaCa-2) and NSCLC (A549) cell lines. Here, MUC16 is linked to familial pancreatic carcinoma.